A Yale grad with no engineering background, Silbermann worked for Google before launching Pinterest with some friends in late 2009. Real-time text feeds were the rage at the time, and some observers felt that an image-based pinboard was doomed to fail. Nine months later, the site still had less than 10,000 users. "I think I personally wrote to the first 5,000 users," said Silbermann, who also gave the site's users his cell phone number and met some of them for coffee. "A lot of people ask, 'Why did you keep going? Why didn't you bail?'" he said. "I think the idea of telling people, 'We blew it,' was just too embarrassing."