You’re being way too reductive assuming that genius level intellect also includes being highly industrious AND has the risk appetite to start a company that will likely fail.
Genius level intellect comes with a lot of problems - pessimism ranks highly because the foresight granted by intellect shows the huge combination of possible failures.
Negative emotion is felt more strongly than positive emotion in all humans so self doubt (illuminated by combinatorial scenario projections) tends to be higher in genius intellect.
Also many of them tend to have other problems at the extremes - anxiety, paranoia, mania, distrust, uncontrollable ego, combinations of these and more - this leads to many of the geniuses taking their paycheque and disappearing into escapism of drugs, alcohol, sex, video games, whatever - just to make it stop for a bit, just a little relief
And some geniuses aren’t industrial at all, and are happy with that, they are happy being kind and reliable and humble, they are not driven by money but the acquisition of knowledge for its own reward.
Maybe they just want comfort and know the statistics on how many startups fail and the insane amount of work and sacrifice a startup requires and it’s actually easier to get a well paying job and be more balanced.
The assumption that genius are always in the capitalistic, money driven, alert problem solving mode is a very American view of live, when indeed, just like intellect is NOT a single scalar dimension, genius is varied and colourful.