He's 26. He went straight from Harvard to Facebook. He still effectively controls Facebook. And he's a billionaire. I don't think he really can take a risk, in the sense that a normal person would think of a risk. As long as he doesn't do something blatantly stupid like run in front of a bus, he's probably set for the rest of his life. Instagram deal not approved, or approved but doesn't "work out"? Shrug. Still a billionaire. And I'm sure he's taken a lot off the table already so even if Facebook's value plummets, he should still be gold.
You think he doesn't have much to lose because at the end of the day he's still a billionaire. I doubt he feels like that. He's got an opportunity to succeed in ways most humans never do. You could argue that he's got more to lose than most, not less.
