12 Sep 2018 Warren Buffett’s full CNBC interview on the 2008 financial crisis ( Portfolio )

"People start being interested in something because it's going up, not because they understand it or anything else. But the guy next door, who they know is dumber than they are, is getting rich and they aren't," he said. "And their spouse is saying can't you figure it out, too? It is so contagious. So that's a permanent part of the system."