If you'd founded a tech company worth billions of dollars, what would you do with your cash?
That's a high-class problem faced by the moguls on this list.
Naturally, many of them buy expensive things, like cars, houses, planes—even islands.
But even if you're Larry Ellison, with a seemingly endless appetite for that stuff, there comes a time when you want to do more.
Maybe it's solving the world's problems, or just indulging in a geeky fantasy.
Disclosure: Jeff Bezos is an investor in Business Insider through his personal investment company Bezos Expeditions.
