Concentrating in a single asset class can be an invitation to trouble. : I try to avoid giving unsolicited advice to billionaires. They are doing just fine without me. Besides, nobody likes to hear from the cheap seats, especially when they just made a terrible, horrible, reckless investing error that poses an unnecessary risk and could cost quite literally billions of dollars. I bring this up after I read the headline “This Billionaire Has Put Half His Net Worth Into Gold” on Bloomberg News, and the story that went with it.