Actually, a lot of people would claim that height is the most important thing in playing basketball. Average NBA players are 78.9 inches tall. Height is roughly normally distributed, this puts them at about 3 SD above mean height. They surely aren't typically 3 SD above the mean in any trait that doesn't correlate strongly with height, and height is less environmentally influenced (and simply simpler) than the traits it correlates with so its reasonable to assume that it is more causal of other extreme traits than the reverse.

How many highly rational people do you suppose there are in the world? How many of them do you suspect are risk-seeking enough to aim for the type of swing-for-the-fences success that would make them notable?

If your respective answers aren't "quite a lot" and "a significant fraction" then it seems like you're neglecting the base rate. Otherwise, I'd like to know how you arrived at those estimates.

If rationality was the most important component of individual level success- the Ultimate Power- then you'd expect pretty much all the most successful people to have above-average rationality. Heck, even if it wasn't, you'd still expect pretty much all the most successful people to have above-average rationality.

Average general rationality is probably a lot less than you'd think. Domain-specific rationality is what determines the success in any particular endeavor, and rather than generating full theory of rationality, simple heuristics and lots of attemptees most likely approximate it well enough and thus produce steady amount of really succesful people.