In 2011, when Emmett Shear pivoted the live streaming service Justin.tv into the video game platform Twitch, people warned him that gaming was just a niche. But unlike his first two ventures, video games were something Emmett instinctively understood: he and his co-founder Justin Kan had been playing them together since they were kids. Emmett built a user base on Twitch by asking streamers exactly what they wanted and giving it to them: revenue opportunities, streamer fan clubs, customizable emoji. As it grew, Twitch attracted users from the darker corners of the web, but Emmett believes the site is first and foremost a way for people to come together and build supportive communities. In 2014, Emmett sold Twitch to Amazon for just under a billion dollars but stayed on as the CEO. Today, the platform has 31 million daily visitors who stream trillions of minutes of live video every year. Not bad for a niche business.