78. Sam Altman

Founding partner, president, Y Combinator

Sam Altman, founding partner and president of Y Combinator, one of the most coveted startup accelerators in the country, has been outspoken this year about his disdain for the rate at which many startups burn through cash. The "mega bubble" in Silicon Valley won't last forever, he said, and he advises startups to spend "almost comically low" amounts of money as the next round of funding may not be as easy to get.

Altman has invested in Product Hunt and BloomThat, among others, and his accelerator is where companies like Airbnb and Dropbox got off the ground. Y Combinator also just raised its first official fund so it can invest in startups in an even bigger way financially.