In 2006, at only 30 years old, Michael Reger raised US$3 million from family and friends to help found Northern Oil & Gas Inc. The young CEO wanted to use breakthrough technologies such as fracking to drill in far-flung regions of North Dakota and Montana. Although his strategy has been criticized as a move that no older, (presumably) wiser CEO would make, the gamble paid off for the fledgling company: It unearthed huge oil reserves in the previously unexplored but now booming area.

Image: Matt Palmquist is a freelance business journalist based in Oakland, Calif.