Before launching Microsoft, Bill Gates was a Harvard University dropout and co-owner of a failed business called Traf-O-Data. Driven by his passion for computer programming, Gates built what would become the world's largest software company. Microsoft went public in 1986, and by the next year its rising share price made then-31-year-old Gates the world's youngest self-made billionaire. An investor in the initial public offering would have seen a return of 30,207 percent.