Steve Ballmer, Microsoft’s CEO from 2000 to 2014, was instrumental in scaling the company from a small 30-person startup to one of the most valuable companies on the planet. Ahead of Microsoft’s 50th anniversary, I had the chance to catch up with my former boss. We talked about the early days of Microsoft and the pitch that convinced him to take a chance on a small company in a new industry. We also discussed how three traits—irrational confidence, realism, and persistence—have helped him succeed at Microsoft and today as the owner of the LA Clippers.