He's an exceptionally good communicator and has very strong soft skills, and applies them to self-promotion. He's also good at politics (as in convincing crowds of people -- not so much at interacting and making long-term connections with individuals). A lot of this has to do with feeling out crowds, and telling them what they want to hear. He's also got a slightly underdeveloped moral compass, which always helps (he was willing to be a little bit sleazy and subtly undermine competitors). That's mostly what it takes to get famous. He was also the only person, after RMS, who was arrogant enough to take credit for the whole movement.