Some of them think that they can change the world inside an organization that gives them the tools and power to do so - one of the best programmers I've met works for Microsoft, he loves Haskell and all that, but worked for the C# team and has moved around inside Microsoft, doing interesting work.

I don't think he'd be a good fit to try to change the world by himself, but he can buy a good vision (or a well-sold bad one maybe :) ).