Facebook's 34-year-old CEO Mark Zuckerberg has dethroned Berkshire Hathaway CEO Warren Buffett to become the world's third-richest person with $81.6 billion wealth, according to Bloomberg. Zuckerberg gained $8.8 billion this year despite Facebook's data-privacy crisis that slumped its stock by 18%. Amazon's Jeff Bezos remains the world's richest, while Microsoft's Bill Gates second-richest.