Say what you will about billionaires, but they're rarely characterized by their humility. Nicolas Berggruen might be the exception. In some circles, he's called the "homeless billionaire." The investor and financier does not own a home, and says he can fit all of his possessions into a paper bag.
Berggruen is undoubtedly the world's richest minimalist. He acknowledges that whatever he owns is only temporary, and regularly speaks out about the spiritual bankruptcy of consumerism. He hopes to impact the world positively by bringing about political change, rather than by accumulating possessions.
Of course, it's probably a lot easier to be a minimalist when you've got a few billion in the bank. But Berggruen at least earns points for not letting his money consume him.