That might be true, but I've gotten the impression that a lot of people who've made FU money aren't necessarily super skilled, but happened to do the right thing at the right time.

I can't give a comprehensive survey of everyone who's made FU money, but take Tim Ferris for example. He's not a whiz at building websites: he just knew to cash in on selling brain supplements online when that stuff was taking off.

Edit: I should point out that I don't think FU money is exclusively about being able to say "FU" to a jerk. I emphasized that aspect just to invert the comment I was responding to. FU money can also just be about ditching a career you're not that interested in (but may be highly skilled at, and otherwise locked into).