Leonhardt examines the payoff from going to college. Daniel Indiviglio adds:
From this, college definitely looks like the right choice. But what does this chart actually show? Not that a college degree was necessary — just that employers prefer them. The value of a degree has become something of a self-fulfilling prophecy: it's become worth so much because people assume it should be.
Let's do a quick thought experiment. In the example above, it's not unrealistic to assume at least 10% of the jobs of "college graduates" didn't actually need the degree for the skills their job requires. Imagine if those 10% of individuals hadn't gone to college. There would still have been demand for the jobs that they took, so who would have got them? Easy — people without college degrees, possibly even the same ones. Just because college graduates earn more doesn't mean that their degree provides them any additional knowledge necessary to succeed in their jobs; it just means that employers found them more attractive because of the degree.