That’s the argument I make in this Forbes piece. College might or might not enhance one’s future productivity; it is not like buying a financial instrument with a calculable yield.

I’ll add here that college can be worthwhile even when there is no monetary return on it. The value of a liberal-arts education does not depend on its “paying off” financially. Students who want such education may find it at some colleges. They can also get it at much lower cost without ever enrolling or taking a single course.