Gavin Andresen

A Silicon Valley refugee in Amherst, Mass., says he worked closely with the person "or entity" known as Satoshi Nakamoto on the development of Bitcoin from June 2010 to April 2011. Andresen, an Australian who graduated from Princeton with a Bachelor's in computer science, eventually became Nakamoto's point person on a growing team of international coders and programmers who worked on a volunteer basis to perfect the Bitcoin code after its inauspicious launch in January 2009. Andresen originally heard about Bitcoin the following year through a blog he followed. He reached out to Nakamoto through one of the Bitcoin founder's untraceable email addresses and offered his assistance. Holding the keys has also made early comers to Bitcoin wealthy beyond measure. "I made a small investment in Bitcoin and it is actually enough that I could now retire if I wanted to," Andresen says. "Overall, I've made about $800 per penny I've invested. It's insane."