15. Warren Buffett
Like other celebrities, Warren Buffett too carries an American Express Green Card. This was revealed in 2013, when the second-wealthiest man in the world stunned the viewers of CNN by taking out the Amex Green Card from his wallet. With a net worth of nearly $73 billion, you would not have expected Buffett to carry a standard credit card, which can be used by average cardholders too. Unlike the platinum or black cards of Amex, the Green Card is for everybody.