Physical is a good reason, and some people pointed that out. Money is another, and of course that kind of training is expensive. Another is, well, SEALs aren't designed for open large combat roles. They wouldn't be much better than the average soldier in that situation, so why bother? SEALs, as are all special forces, are designed for specialized modes of warfare. Their training isn't going to buy you much in the GI role on the battlefield, but it will when it comes to deep penetration, intel gathering, grab'n'go missions, and the like.

Using SEALs on the open battlefield would be like using a swat team to do a routine traffic stop. They won't do it any better than a regular cop, so there is nothing gained there.

One more big reason why everyone in the military isn't trained like a SEAL...mental. Not physical. Mental. The guys that make it to BUDS, and most importantly make it through BUDS, have a mentality that cannot be taught and cannot be trained. They are special people, and every single SEAL I have had the pleasure of knowing was very intelligent and very personally motivated. Having muscles or being a workout monkey had absolutely nothing to do with it. They were incredibly driven, smart guys that had this insane ability to will themselves to do things that even an above average guy could never do.

And they are a little wierd. In a good way. But they are just different.

From those selected to train the attrition rate is crazy! I believe way over 80%. If you tried to take the average soldier in mass and train him like a seal the attrition would be 99.99. The biggest difference between a regular soldier and a seal (IMHO) is mental toughness. These guys don’t look for reasons to succeed. They dig down deep and find reasons never to fail and let their buddies down. Regular infantry in the US army is trained in a few months. Seals take over 2 years. Not to mention when they are not on mission they are training . Regular soldiers when not on mission might train 20% of the time. The rest of their time is spent doing admin crap. But believe it or not it’s way more than most soldiers in other armies of the world get.

1. It is hellaciously expensive per person.

2. Only a small percentage who volunteer for it actually pass, so we'd either have a tiny military or need a vastly different recruitment system (one in which we had enough recruits/draftees and enough incentive to endure the training to get about seven times the number of SEALs we currently have)

3. Do you really need all of your interior electricians SEAL trained? Your human resource technicians? Your multimedia illustrators? That's valuable money/time/resources wasted on SEAL training that could be spent of training for their specialty. Why give a fighter pilot SEAL training when he could be training for, you know, fighter piloting?!

4. Worse, you'd lose some of your best candidates due to that training! (How many excellent dental specialists or network technicians would you lose because they couldn't pass Hell Week?)

5. Finally, and this is the crappiest, most uncomfortable one: the nature of war has always been that you need "cannon fodder". Yes, that is a shitty way to think about it. But it's sadly true. Unless you have unlimited resources, you can't afford all that training for soldiers you know are going to have a high attrition rate. One of the many reasons that rational, humane people try to avoid war.

(Now I'm imagining a TV show about a SEAL team made up of a multimedia illustrator, a dental specialist, a logistics person, and a construction vehicle mechanic. There would be hijinks! I want royalties, Hollywo0d!)

There are a lot if reasons, but to start with, you need to understand the difference between a conventional warfare force and an unconventional warfare force. Conventional forces do the stuff you think about when you imagine warfare- they assault big targets like cities and enemy bases. Unconventional forces make small, surgical strikes against targets like enemy leaders, high-value intelligence targets, and other things to make it hard for the enemy to keep fighting effectively. Unconventional warfare also means making contact with friendly forces opposed to your enemy, gathering intelligence, and a wide array of things that conventional forces aren't that good at. That's an oversimplification, but it's a critical idea to have in mind in this discussion.

The battlefield calls for a mix of conventional and unconventional warfare to secure victory. Training every soldier to be like a SEAL would ultimately be a waste of time, as the bulk of your forces are going to be used in conventional ways. Only a very small percentage of your troops are going to engage in unconventional operations. It's like asking why surgeons are seldom sent down to the ER to triage incoming patients. Yeah, they can do it, but their time is better spent preparing for and performing surgery. Why go to all the trouble of recruiting, training, and employing a hundred surgeons when you can employ five surgeons, ten doctors, and eighty-five nurses instead. The nurses will do most of the regular work, freeing the doctors and surgeons up to do what they do best.

Finally, it's worth noting that more than 85% of the volunteers (and it's all volunteers) who go to SEAL training either fail or quit the program. Until we get to the point where we have Mobile Infantry in power armor, if we flunked 85% of all our military recruits, we'd barely have a military at all.

The most simple answer is very few people are capable of operating at that level. Why don't all men play football? Why don't all college players go to the NFL? Because as you select people using more and more difficult grading standards it gets harder to find people capable. In 2014 the pentagon released a study saying 7 in 10 high school graduates were not fit for military service. From there more wash out in boot camp (15% according to military.com) and even more wash out in their MOS schools like the school of infantry. Now you have a pool of fairly fit, intelligent, mentally tough people and of them a very small percentage of the fittest and most motivated even ask for special warfare training an additional 75% wash out and return to their previous unit. SEALs and Recon are not just good because they were trained well they are better because they were already tougher, smarter and faster than you then refined that ability for years. It's something you simply can not mass produce.

First, it would result in a terrible US military, one in which we would be incapable of fulfilling most of our treaty commitments. Why? B/c the vast majority of people who enter SEAL training flunk out. Ever tried swimming across a pool underwater with cinderblock tied to your ankles? Or going through a week of mental and physical abuse while averaging 3-4 hours of sleep per night? If all warriors had to go through SEAL training you'd have about .1% complete it. Unless you lowered the standards. Which would defeat the purpose. Or unless you didn't make it required that they pass (which would mean there would be no consequence to failure). So to offer a quick summary of this point, if we required all US military to attend SEAL training and pass it, we'd have a US military of probably 20,000-30,000 warriors tops. That would be totally inadequate for national defense. It would have meant we could fight only asymmetrical or unconventional conflicts. Our land force would be incredibly small and very limited.

Second, the OP doesn't understand what makes a SEAL a SEAL. Yeah, the training is good. But that's not actually the deciding factor b/c almost all special operations units around the world have very similar training. There are a range of other issues (such as: motivation, teamwork, more interest in mission than career advancement, tactics) that matter far more than just being physically fit and a lot of small unit CQB training. So you could train every person wearing a uniform in the US military and most of the people who passed SEAL training wouldn't be accepted by the SEALs (or other US special operations units) b/c there are so many other factors other than the training that determine if someone is a good warrior. Let me try to explain this concept: training addresses only two elements of your performance...your skills and your knowledge. It doesn't address all of the other factors that go in to how good you are. The US trained the Iraqi Military and we equipped them. They had a 10-1 advantage against Daesh/ISIS/ISIL/IS at Rimadi in Iraq plus superior firepower (armor against pickups). And they ran. They threw down their arms, took off their uniforms, and they ran. They refused to fight. Just b/c you send people through SEAL training (and some of them pass) doesn't make them SEAL equivalents...that's why entrants into BUDS aren't done by a draft but you volunteer/apply and then you are weeded out even before training starts and even then you can be RTU'ed or kicked back if the cadre determine you're in it for the wrong reasons or lack what they want. This is true of all of the US special operations units.

Third, most of the training isn't relevant to the roles of the US military. Let me ask the OP: why doesn't the military require very solder go get a PhD? Or learn how to fly an aircraft? Or to become a medical doctor? Or become a veterarian? Or a dietician? And the answer (the same as the one to the OP), b/c those skills aren't that relevant to the MOS of the vast majority of warriors. Seriously....BUDS is an irrelevant skill to the vast majority of people in the US military. Just as being a helicopter AC is critical...if you're going to fly a helicopter but not that relevant for other MOS roles. This last point goes to the mission or speciality of the troops involved. SEALs are special operations troops. The premier special operations units (that receive training beyond that which the SEALs go through) are ACE (what the public knows as Delta Force) and DevGru plus also the US Special Forces (Green Berets) who specialize in counterinsurgency and have capabilities that the SEALs are not trained to do or have and the USAF Pararescue units. SEALs are trained to do special operations. It is a waste of resources to ask them to fight a conventional war (say....put a squadron of seals against an Iraqi armored division or a Russian Mech unit).

Last of all, why did the OP pick the SEALs? SEAL training is hard, I'll grant you that. But I'd argue that ACE, DevGru and the Pedros all have a far more rigorous selection and training program--most SEALs wouldn't qualify for any of these units. Indeed, efforts to expand DevGru have been stymied b/c not enough SEALs are good enough for DevGru selection. ACE can select SEALs for their Q course but very few get selected to even try out for the unit. There are some former SEALs in the USAF Pararescue teams not they don't dominate--there are even more former US Marcomm, ACE, and Ranger types with the Pedros.

There’s a very good reason why Navy SEALs command so much awe and respect, which is also the reason why there are so relatively few of them: most people could never finish their training.

Graduating from Parris Island and earning the right to call myself a Marine was far and away one of the most challenging thing I’ve ever done in my nigh-on 50 years; I’d say the overwhelming majority of current and former Marines would tell you likewise if you asked them. I knew a couple of guys when I was in who completed the Marine Corps Scout/Sniper program; they had some pretty entertaining stories about what they had to do to accomplish that. The basic Infantry Officer Course at Quantico— “grunt school” for newly-minted Lieutenants who wish to lead Marine riflemen in the field— has an attrition rate typically hovering around 25% or thereabouts.

None of these, to my knowledge, comes anywhere near to being as much of a complete and total bitch to successfully navigate as the Navy BUDS course. Assuming a candidate can pass the rigorous selection process to have a go at it in the first place, the rate of failure tends to be about 75% to 80% for each class.

Spending millions of dollars on highly-specialized training with a fairly narrow scope of usefulness that maybe 1 in 4 people have even a prayer of mastering is not a good way to build and maintain a standing military of the sort that most large, “First World” countries require to defend the home turf and project the will of it’s leadership abroad…never mind one as massive as the US military.

Also: for a military recruiter, convincing a sufficient number of soft, spoiled, slack-assed American 18- or 19-year-old to forgo a life spent largely doing stuff like waking up at noon, performing keg stands, and getting in sorority girls’ panties in favor of submitting to the rigors, hardships, and personal sacrifices of military life is already a fairly tough sell.

Well, come to think of it, most young men crazy enough to want to enlist in Marine Corps have convinced themselves by the time they’re old enough to join; it sure was the case with me.

Be that as it may: considering how challenging it can be to get some young man or woman to sign on the line that’s dotted for a four-year enlistment contract, imagine trying to do so after showing them videos of Navy BUDS instructors forcing sailors to do things that would otherwise get them indicted by Amnesty International and saying “Looks like fun, right? Well, that’s just the stuff the Department of Defense allows me to show you. So, young John/Jane: whaddya say……?”

Anyway: even if everyone had a decent chance of finishing Navy SEAL training, it would be an almost entirely useless and pointless waste of time and resources. In a world where it might be possible for SEALs to perform all the tasks that require doing in order to complete missions and meet objectives, it still would be.

Sure, you can take two dozen snake-eaters and have them sneak into another country and bag the world’s most wanted terrorist. But someone needs to fly the chopper to get them there. Someone needs to maintain everything on the chopper from the engine to the hydraulics to the avionics so it doesn’t crash en route (yeah, I know: one of the Blackhawks used in Operation Neptune Spear ended up ditching in Abbottobad…this is a hypothetical exercise).

Someone needs to survey and recon the terrain to plot the best route to get in and then “exfil” with a quickness. Someone has to jam the other country’s air defense systems so they don’t get wise to the uninvited guests in their midst. Someone needs to drive them to the airfield. Someone needs to keep the truck they’re riding on in tip-top shape. Someone has to feed them. Someone has to make sure that the information systems used to transmit data related to the mission and provide a real-time satellite feed when it gets going are working and not getting hacked by someone working for the bad guys. Someone needs to help anyone who gets wounded during the op stay alive and heal.

I think you get the idea. A top-notch, well-run apparatus of national defense is a team effort that requires a large number of dedicated professionals with an endless variety of talents, skills, and abilities to come together in concert and do all that needs doing to ensure that the guys who ultimately do all the trigger-pulling succeed. And 99% of those jobs don’t require a fearless, snake-eating commando to perform. The relative minority of direct combat troops and special operators who do the stuff that makes for exciting war movies can’t get the job done without the help of dozens, hundreds, or even thousands of fellow military professionals performing the comparatively mundane and non-sexy work critical to supporting their mission.

Lots of reasons: Expense, requirements, readiness, supply-chain, but probably the most important:

There is not a SEAL in every sailor/soldier.

A SEAL is a weapons platform all unto themselves. There are extreme physical requirements which not everyone can meet. There are extreme emotional requirements which very few can meet. Despite the stereotypes, the intellectual requirements for special forces work are quite steep.

Then there is the whole question of "Spirit." A Navy SEAL is just "hitting the zone" right about the time most people would turn into a quivering pile of various bodily excretions. Our whole society is geared towards beating the spirit OUT of people, these days, especially in our public education system. SEALs are called up from the ones who still have it.

There is also the component of "Faith." They do clandestine work. They go in to foreign countries, destroy things and kill people, and they often do so not knowing why and with the understanding that they may NEVER know why, but doing it simply because it needs to be done.

A soldier is a different element entirely. Where the SEAL is an endoscope, soldiers are a battering ram. They overwhelm and annihilate, not do precision strikes.

If you have one small group of people being a real problem and hiding out in a residential area with a bunch of school children as "human shield," SEALs will take care of that real quick, and most of the neighbors won't know what happened until they see it on the news the next day. If you have a hundred thousand armed men threatening the border, then the US Army will leave a large, smoking crater marking where they were at.

Others have covered the issue of cost and as such, I would focus on a different aspect. Requirement.

Out of all the members of the US military in operational service today, the majority of them simply DO NOT NEED THAT TRAINING. No, really, just think about this for a moment. How often is a computer tech guy going to perform the duties of a Navy SEAL? Or a pilot? Or a tank driver?

When it comes down to it, the chances of them ever engaging in any situation where this training is needed would be none-existent and essentially useless. Furthermore, it would take away training time from stuff that they WOULD need to know. Things like tactics or technical details. And of course, to retain these skills, they would need to train on a regular basis.

Then we come down to the NATURE of the SEALS and other special forces. SEALS (and their counterparts the world over) are not primarily trained for conventional warfare and do not typically engage in conventional warfare. It's not that they can't, but rather that they prefer to avoid such confrontations. One of the principle reasons that SEALS and other special forces are so effective is that they rely on surprise and speed to succeed, rather than simply outgunning their enemies.

Finally, there is the issue of the nature of selection for special forces units. I am not sure about the SEALS, or whether this still applies to the SAS, but the last I heard, military personel are required to have spent TWO YEARS in the army before being considered eligible to apply for the SAS/SBS and I suspect the same is true for the SEALS. And there is a pretty high failure rate for those guys. Now imagine trying to do that with a group who were civilians only days earlier.

Yeah, really not going to work that well.

There are a variety of reasons why you can't.
1. Physical. The military is oriented around the average young adult male. (Yes this is sexist, but men have always been on average significantly stronger than women, and strength has always been an advantage on the battlefield. Always). Then there are the exceptional warriors, the individuals who are physically, mentally, and emotionally gifted at warfare. Here you start with the 1 in 10 rule which goes back to Alexander I think. People who will go longer, fight harder, etc. These people are better than average. They have more to begin with. They can take a harder "normal day".
2. Expense. Others have mentioned this factor, but I think Richard Marcinko (father of DEVGRU/Seal Team 6) said it best in his book: DEVGRU has an ammo budget equal to the Marine Corps. That's freaking impressive. It's also a huge expenditure. And this is without going into specialized equipment, which is at the minimum best of breed.
3. The nature of warfare. Special Operations plays an important strategic role, but you can't win wars with it alone. Not every action is suited to special operators. In fact, wars are mostly won by well-disciplined, well-trained, and well-equipped 'average' troops. Why? There are 9 times as many.

For almost the same reason why not every undergraduate Biology student with hopes to become a physician will make it to medical school.

There isn’t an infinite source of money and material resources, therefore it’s financially impossible to train every servicemember to a special operations-capable level. Time and manpower are two other important elements of a successful training regime that are finite in quantity. Furthermore, it’s non-sensical to bother spending resources into training everybody into an elite warfighter when almost every one of the trainees will fail out of the course. This isn’t to suggest that the majority of the military population is incompetent, rather to state that not every person has the interest and burning passion to train and serve at such a high capacity. Willpower is everything when pursuing elitism. Candidates who eventually go on to graduate BUD/S and then SEAL Qualification training see two options throughout their time in the Naval Special Warfare cirriculum. They either graduate with a Trident, or they lose their lives trying. As you can see, neither involves failing.

Nicklaus has the correct answer. Mostly the expense would be intolerable to the military budget, but if you think about it, in the Marine Corps only about 20% of Marines are Grunts, meaning infantry. Every Marine is trained to be a rifleman, but not a Grunt. The various Services spend their budgets providing the training for the individual’s job, know as his/her MOS or Military Occupational Specialty. It’s not much use training an electronics tech as a Navy Seal which would be wasted. Best reason I can give is that Navy Seal and other special forces qualifications are so stringent that only a small fraction of those in the services could qualify. Be the best you can at what you do.

Because special forces have much different tasks than regular soldiers, and the fact of the matter is that it is unnecessary and would be more of a burden on the military than beneficial.

The Navy SEALs and other special forces units have their own missions, special operations, which includes infiltration, hostage rescue, and other missions that are not performed by regular units.

To top it off, the vast majority of servicemen are not combat personnel; they are support personnel.

Most of our servicemen (in the land Army, that is) are not even infantry soldiers, and while their jobs necessitate going out into the field and thus, military training to be able to survive and protect themselves, the vast majority are support personnel and are responsible for logistics, food, supplies, fuel, tech, weapon repairs, truck driving, transportation, and so forth.

What sense would it make to have someone in one of those lines of work trained as a Navy SEAL? And you want to put all branches through SEAL training?

SEAL training is there to eliminate any candidate unsuited for the mental/physical rigours of the job. The truth is that the vast majority of jobs in the military are nowhere near as damanding as special forces, and I am talking about the land forces (Army and Marines).

If you look at the Navy (most members are in the fleet), what sense does it make to train all of them like SEALs?

The same with the Air Force. Most of the Air Force are support personnel and why would you want to train a jet mechanic/repairman as a Navy SEAL? What does that have to do with his job description.

In this day and age, it is important for the military to realize it needs both "teeth" and a "tail". The "teeth" are the weapons and soldiers at the forefront of combat - they are ever sharper and deadlier, and require a longer "tail". For every jet fighter and pilot, there are dozens of engineers, mechanics, weapons technicians, and others making sure the plane is ready to fly, armed, fueled, and that it provides the best chance of the pilot succeeding in the mission and returning back to fight another day. This is true as well with Navy SEALS or other special forces - they need training and support and for each one of those elite members, there are dozens who provide the necessary support.
Think of it this way - a US Navy Aircraft Carrier has in excess of 4000 sailors on it. Not all of them are pilots or weapons officers - some of them will perform the mundane but necessary tasks of feeding, clothing, or healing (not to mention delivery mail or providing haircuts for) those 4000 sailors - the are no less important because without that strong foundation, the "point of the spear" cannot do what it is intended to do in today's world - when necessary, it will strike hard, fast, and with precision - and a lot has to go right for that to happen.

Well, for one the “failure rate” for BUDS ( Basic Underwater Demolition School ) is over 80%…It is not unusual for a class of 150 to get whittled down by the end to 20..or less. Then they go onward to multiple schools…jump school, advanced medical training, radio, weapons, etc. of that, another 50% fail or get injured such that they cannot continue. After that, the remaining go to their respective units where they QUALIFY to become a SEAL and wear the Trident insignia.

To put this in a numbers category…..200 in basic training…of that 40 finish up the basic course. Of those 40, 20 disqualify by failure in schools or injury. 20 remain and go to their units where another 6 do not make the cut of qualifying as a SEAL. In essence, the cost and the numbers to get our military to be one huge SEAL unit would be ASTRONOMICAL. Not to mention, it is tougher I hear to keep Medically qualified as a SEAL than it is to get in. Most have to leave SEAL Active units because of injuries sustained in training, actual missions, or just plain worn out!

So, I was NOT a Seal, I was a sailor.
But at one time, I worked on equipment that they used. One night, I had to do an emergency repair to a starter motor (Easy fix) and reinstall it on the small boat that they were working on.
Went to the fantail and looked down (Aircraft carrier, stopped.. 6′ swells, ROPE LADDER (and a 50 lb starter motor)

This is NOT something I trained for. (No way in hell could I climb down a rope ladder holding that starter, into the darkness, to a boat that kept jumping up 6 feet)

In this case, the Seal team took a look at me looking down and realized that if I even tried, I would end up dog paddling while the starter headed into the depths. So, one of the seals (an EM rating) took the starter, popped it on his shoulder, and scampered down the ladder into the boat like I would walk down a flight of stairs.

Sure, I could have trained as a Seal. But that would have been the ONLY time in my entire career I would have needed that level of skill. Which would have been a waste.
They DID train me to be able to rapidly diagnose and fix the starter. That, I did fairly often.
The US Army(Soldiers) has a role that is quite different then that of a Seal. The Army does not need people to excel in 4 man operations. Don’t need to teach them how to use kit they will never know exists. Don’t need to teach them how to get hooked into a fast moving rib, Halo jump, use a rebreather, or any of the other things a Seal needs to know. There is also a difference in fire fighting techniques. Army ammo discipline is out the window. Seals seem to put a lot more lead downrange, but it is targeted.

In the end, you train people for the jobs they will perform. I mean… I was on an aircraft carrier, but I did not need to train to be a pilot (Well, almost, but that’s another story)

Because the Military needs a huge variety if roles to be filled, and missions to be undertaken. I don't need to train cooks to kill people and disarm or plant explosive devices underwater. I don't need truck drivers trained to HALO jump. The military missions are huge, diverse, and vital. Asking why we don't train them all like SEAls is a bit like asking a mechanic why he doesn't only have hammers…make sense?

Let me put it another way. The US Army Infantry is an incredible fighting force. With the full Division deployed, you have a huge array of death and destruction staring you right in the face. Let's assume no air support, just for this example. From 14 Mike's out, the artillery starts to land around you. Humungous, high explosive rounds dealing total destruction from the air. Multiple rounds littering the sky and destroying virtually everything in range. Somehow you navigate thru that and become engaged by fast moving armor and tanks. High speed, large caliber rounds firing from the most advanced main battle tanks in the world farther decimate your numbers. Somehow, you get past those, and the Stryker's, and the heavy weapons, and the antipersonnel security, AND the mortars. Now you are FINALLY within small arm range, now and only now are you dealing with an infantry unit. And behind them, we have brave men and women that provide clean drinking water, secure bases, secure communications, runways, food, logistics, equipment, fuel, bullets, etc. Plus, command structure. And even then, we haven't talked about all the NON COMBAT roles the military performs as well. So, there you go. For every tier 1 operator, a whole team of support personnel work diligently to keep that shooter in the fight. And those people are fantastic and amazing at their jobs as well.