Scott Adams suggests not trying to become the best in the world at one thing but, rather, to get in the top 25% of several things. He says, “I layered together several mediocre skills that the combination of which made it powerful… So I could be a mediocre artist, an okay writer, not even the funniest person in the room, and I know a little bit about business. Put those four things together and you have the Dilbert comic – something that has great economic value.”
I would argue he has still become the best in the world at something: the best artistic and comedic businessman cartoonist. The idea is that you build a niche for yourself at which you are the best in the world. Become a “subject-matter expert” through being a “jack of all trades”.