Forbes reports that Facebook founder, Mark Zuckerberg is now the world’s third-richest person alive. He has passed Warren Buffett. 34-year-old Zuckerberg is worth 81.6 billion dollars, that's about 373 million more than Buffett. For the first time, the world's three richest people are all tech titans-- Amazon's Jeff Bezos at 141 billion. Bill Gates with 93 billion and Zuckerberg.