He is half right. The issue was that very smart people were building models for assets that they did not understand. We were far better off when the best mathematicians were studying physics and the like.
Example from Michael Lewis who wrote Liar's Poker:
But he couldn’t figure out exactly how the rating agencies justified turning BBB loans into AAA-rated bonds. “I didn’t understand how they were turning all this garbage into gold,” he says. He brought some of the bond people from Goldman Sachs, Lehman Brothers, and UBS over for a visit. “We always asked the same question,” says Eisman. “Where are the rating agencies in all of this? And I’d always get the same reaction. It was a smirk.” He called Standard & Poor’s and asked what would happen to default rates if real estate prices fell. The man at S&P couldn’t say; its model for home prices had no ability to accept a negative number. “They were just assuming home prices would keep going up,” Eisman says.
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