
I have done a massive amount of drugs.
Predominantly crack (smokable cocaine), which I do frequently now, and which is a very expensive habit. I used to spend from $300 to $500 a week for about 10 months, I have been using it for 9 years, I now use it about 1-4 times a week and spend about $300 a week, half of that on heroin.
Crack is by far the most addictive drug. Meth would come (a distant) second. Heroin is joke (a myth actually). Heroin is not addicting at all except as something you've fallen in love with (I've done a lot of heroin, cigarettes are more addicting than heroin).
Crack addiction occurs when recovering from a high, it can be extremely painful when recovering, it'll last from 1 to 3 hours. Your thoughts could be completely insane: the very worst that schizophrenia can be. That is why people would do anything to get another hit: so it can heal the pain and they can be better prepared to recover from it, which can be done peacefully if you're prepared... So what I am saying is, there are two kinds of addiction, the "recovery addiction", which is painful for 1-3 hours and you need more of the drug, which is crack and meth, and there's the "fallen in love" addiction which is how I describe cigarettes and heroin: they are mostly lifestyle addictions. The "recovery addiction" will have you do all kinds crazy shit: you will drive massively far early in the morning to get a little more, you will empty your savings, etc.
I've been there. So how does it feel? Well, when you do stupid shit like I described you feel stupid and can't believe you'd do something so completely stupid just to get high, but when you don't lose your cool and don't do anything you regret then having a drug habit isn't bad, it's fun and rewarding in its own way, that's why I come back to it.