Mark Zuckerberg: The way people start companies in Silicon Valley 'feels really backwards to me'

Facebook CEO Mark Zuckerberg is a CEO who knows a thing or two about building a billion-dollar company. And he thinks a lot of people in Silicon Valley are doing it backwards by focusing on building a company before knowing what they want to do.

"So I always think that this is kind of a perverse think about Silicon Valley in a way, which is that people decide often that they want to start a company before they even decide what they want to do, and that just feels really backwards to me," Zuckerberg said in an interview with Y Combinator president Sam Altman.

Zuckerberg says he never set out to build a company. Even after he had raised venture capital and the idea was taking off, Zuckerberg was insisting that he was going to go to back to Harvard.

That never happened, and Facebook is now used by more than a billion people every day. It took that belief, though, to get him through the tough times.

"I always think that you should start with the problem that you're trying to solve in the world and not start with deciding that you want to build a company," Zuckerberg said. "And the best companies that get built are things that are trying to drive some kind of social change, even if it's just local in one place, more than starting out because you want to make a bunch of money or have a lot of people working for you or build some company in some way."