The most important thing is to be different from others. Do something better than anyone else in the world that's useful to others (even if what you do best has a very tiny niche).

Being able to do something that 100 million other people can do, while potentially important, is likely not nearly as valuable as having a skill that is unique.

Of course, certain unique skills will have more value than others. But it is hard to know which skills will and will not have long-term value since the world will change.

One easy way to create a unique skill is to combine two seemingly unrelated skills into one skill. Being the best computer scientist in the world is really hard. Being the person who knows the most about dolphins is really hard. But being the person who best knows about the intersection of software and dolphins is accomplishable. You might end up writing the best software that tracks dolphins. Or you might use your knowledge of how dolphins communicate over long distances to change the way humans communicate.