who said it? #143 economic theory meets humanity

The irony was that the reason he'd survived was that he'd tried to lie. The two lies--his and hers--had canceled each other out, and Gabriel had inadvertently told the truth. If he had told Lenka's "truth," as she had doubtlessly expected, he'd have committed securities fraud and wrecked his personal portfolio. He'd have lost his job at Calloway. Lenka had lunged and she'd missed, because he was lunging in another direction. The lesson was fantastically cruel to everyone involved. He'd arrogated to himself a victory, but that victory had (fatally) been built on the assumption of her fidelity.

He'd always known that this was why game theory didn't survive studies of real people. Real people's motivations were too complex and flawed to be fathomed by any mathematics.

p. 252 of A Young Man's Guide to Late Capitalism: A Novel, by Peter Mountford (a novel set in La Paz, Bolivia)