We (meaning CS types who follow startups) are an unusual crowd. We're introspective and understand human societies and ourselves better than a lot of people do. Our main motivation for wanting money is (a) autonomy, and (b) building cool stuff. It's ambition that drives us, and we'd still work after a huge windfall-- we'd simply work on much better terms, and probably a lot harder (because such wealth takes out the "had to pay bills" excuse for typical middle-class underachievement).

The motivation for most (98%) people who want extreme wealth to want it is social status. That's not always a nasty thing. Sometimes it takes the form of extreme generosity, or large donations to children.

That's why the sensible path is so rarely followed. These aren't stupid or bad people. They try to use their money for its only remaining purpose (social status) to most people at extreme levels, and they get into a self-destructive loop, because high social status itself impairs judgment and leads to more recklessness.