Investor Ken Langone's parents worked as a plumber and cafeteria worker.

Net worth: $2.1 billion (as of Sept. 2013)

To help pay for Langone's school at Bucknell University, he worked odd jobs and his parents mortgaged their home.

In 1968, Langone worked with Ross Perot to take Electronic Data Systems (HP) public. Just two years later, he partnered with Bernard Marcus to start Home Depot, which also went public in 1981.