Why do the rich want to get richer? Why when you’ve got a million or even a billion do you want more? Mike Williams asks a multi-billionaire and a multi-millionaire what drives them to keep making more money. He also speaks to a banker, who looks after the wealthy and a football agent, who represents high paid players and tries to discover whether the rich are different from everyone else.

(Photo: Image of a superyacht believed to belong to a Vodka Tycoon. Credit: Phil Walter/Getty Images)