There is obviously some minimum level of competence and intelligence required to be wealthy (not losing all of it), but for many becoming fabulously wealthy is as much a matter of circumstance than anything else. I would guess most people here would also be billionaires if they had the same opportunities and circumstances as Musk.

I don't think there's a minimum level of competence even. You can get very wealthy by sheer luck and timing.

Also, a lot of wealthly people aren't stupid like we think. They're evil, which is different. And being evil is actually pretty good for being wealthy. Most people are encumbered by their morality. Evil people are not, so they can do much more.

This reminds of me the following wonderful Numberphile video [1] where they compare the success of billionares to gas molecules: "everybody is just bumping around randomly but the one person that, you know, that became a billionare or something--they wrote their autobiography 'how I got here, all the great decisions I made to beat everybody'... It was just random." I've always wondered whether it would be possible to compute the expected number of billionaires with a model like this. If the number is higher than the expectation, well ok, some fraction of them are consciously steering themselves into billionaire-hood. Otherwise, it's probably dumb luck. It's a fun null hypothesis.

[1] https://www.youtube.com/watch?v=BvwgdrC8vlE&t=57s