The realization that you achieved as much as one could hope to achieve and you still didn't find contentment.

That's honestly, to me, the saddest thing about the mega-rich. They don't know when, or how, to stop. There's no goal state where they can say "ok I made it, I can turn it off and enjoy life now, or at least stop fighting tooth and nail to hoard even more bigger numbers."

For individuals, though, might competitiveness often be driven by insecurity, and the point stands?

Point is that competition is fueled by insecurity. If you are happy, truly content, with yourself you will find competing extraordinarily tiresome and unnecessary. Not saying it’s good for society by the way. I think our civilization needs the pathologically insecure to be disruptive and create room for innovation. Related traits are narcissism and psychopathy. Painful, but useful, in small doses.

Musk, Altman, Bezos they are basically caricatures.