“ ‘The greatest mistake of all investors is to think that what has done well lately is a better investment rather than more expensive. And what has done worse lately is the worst investment — get me out of it! — rather than it’s cheap.’ ”

That’s Ray Dalio, the billionaire behind Bridgewater Associates, talking about where investors tend to go wrong in the stock market.

“Unless you know how to deal with the differences of those, which most people don’t, they’re going to be in trouble,” he said in a Ted Talk appearance earlier this month.