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.

"He's not saying it's the sunk cost that provides the value"

Actually, that's exactly what they said and I even quoted them on it.

It should be clear to you that he meant that they are valuable because they have at least an education. You are being pedantic.

What's the future cost of getting a college grad to become productive? Nothing.

Future cost of making a baby productive? ~20 years of varying levels of investment.

The point is that the cost of the college grad is not a basis for economic decision making. Once the cost has been accrued, it's sunk. If we're making a decision based on whether or not we want to sacrifice the baby or the college grad, we can't take into account sunk cost of the college grad (if we're using economics as the basis of our argument).

> The point is that the cost of the college grad is not a basis for economic decision making.

The common assumption that ajmurmann and vasiliys are likely working form is that value has been retained during the ~20 years of investment and the cost is proportional to the value and there cost is a reasonable proxy for value.

It is an assumption that does not always hold, but is common enough to do as a first order approximation.

But because we are not making an investment decision, there is no sunk cost fallacy. If we have two widgets and invest a lot of money into making the first widget better, and indeed it becomes better, it is not a sunk cost fallacy to call the first one more valuable.

You are citing things but your argument is nonsensical.