Former Microsoft CEO Bill Gates was ranked No. 1 on the 2015 Forbes Billionaires List with a net worth of $79.2 billion. (Nati Harnik / Associated Press)
Mexican tycoon Carlos Slim Helu was ranked No. 2 on the 2015 Forbes Billionaires List with a net worth of $77.1 billion. (Jeremy Piper / Associated Press)
Berkshire Hathaway Chairman and CEO Warren Buffet was ranked No. 3 on the 2015 Forbes Billionaires List with a net worth of $72.7 billion. (Nati Harnik / Associated Press)
Charles G. Koch, chairman of the board and chief executive officer of Koch Industries Inc., was ranked No. 6 on the 2015 Forbes Billionaires List with a net worth of $42.9 billion. (Mike Burley / Associated Press)
Americans for Prosperity Foundation Chairman David Koch was ranked No. 6 on the 2015 Forbes Billionaires List with a net worth of $42.9 billion. (Phelan M. Ebenhack / Associated Press)
Christy Walton was ranked No. 8 on the 2015 Forbes Billionaires List with a net worth of $41.7 billion. (Alberto E. Rodriguez / Getty Images)
French billionaire L’Oreal heiress Liliane Bettencourt was ranked No. 10 on the 2015 Forbes Billionaires List with a net worth of $40.1 billion. (Francois Guillot / AFP/Getty Images)
