I'm more inclined to agree with mere multimillionaire DHH on the the motivations of billionaires[0]:
> I can thus completely understand why the likes of Elon Musk or Mark Zuckerberg continue to show up for the daily cage match of running high-profile companies. Why the appeal of sitting on a beach is limited to that of the occasional break, not a permanent arrangement. It's because the drive that got them to where they are isn't extinguished by achieving personal, material wellbeing.
That said, I had not considered that, for some, keeping themselves on top of the capitalism leaderboards might also play a petty role.
I think there may be some credence to the Dark Triad[0] theory as well.
[0] https://en.wikipedia.org/wiki/Dark_triad