Barack Obama and Mitt Romney both spent around $1bn on their 2012 presidential campaigns. Rather than fund a candidate in 2016, New York billionaire Donald Trump decided to stand himself. “My income is $400m a year,” he claimed. “Sure, I would spend it [on campaigning].” In 1992 billionaire Ross Perot promised to “buy the White House to give it back to Americans who can no longer afford it.”