When he sold Carnegie Steel in 1901 for $480 million, that made him the richest person on earth. That would be the equivalent to $400 billion today. That would make him richer than Elon Musk, Jeff Bezos or Bill Gates. After selling the company he devoted his life to giving away 90% of his fortune, funding over 2,500 public libraries, Carnegie Mellon University, Carnegie Hall in New York City, and The Carnegie Foundation. His belief: "The man who dies rich dies disgraced."