He has a perfectly valid economic argument. He's not saying it's the sunk cost that provides the value, it's the added overall value they provide by having a co

He has a perfectly valid economic argument. He's not saying it's the sunk cost that provides the value, it's the added overall value they provide by having a college education. The cost of getting that education could be a reasonable proxy for the value of the education, though imperfect. People usually make the sunk cost mistake when they aren't evaluating the immediate potential of the options, just the emotional tie to the money invested. That's not the case here.