Getting extreme wealth is more so about luck in various forms than competence/intelligence. If it were just about the latter everyone who's intelligent/competent would be rich. You don't hear about boring wealthy people either.
Competence, intelligence, merit have little connection to wealth. Wealth at that level is attained through arguably unfair means, not from reward for hard work. Conversely, poor people are not poor as punishment for lack of intelligence or merit
In many cases the GPs are not, at least nowhere near as much as you’d think. Obviously there are power laws here as well. Non partners, forget about it.
The other thing is it is maybe the most nepotistic industry out there. Which somewhat makes sense given the actual job is so relationship based.
https://en.wikipedia.org/wiki/Affinity_fraud among other factors - being someone who talks right and plays metaphorical ball with the correct people matters more than any amount of intelligence or competence.