I think part of the problem is that the people who get into an industry to make the world a better place understand that they need to maintain long-term control of their company to achieve that goal, and see that traditional VC funding is somewhat antithetical to that objective. There's no big payout for a VC that takes a minority stake in a company that may never go public and whose goals are probably to provide low-cost services to poor people in developing countries.

If you're bright enough to change the world, you're probably wise enough to anticipate the collision of these two worlds.