Discussed here.

^College is often described as a path to prosperity, but is it? A college education can help people make more money in three different ways.^

^First, it may actually make them more economically productive by teaching them skills valued in the workplace: Computer programming, nursing or engineering, say. (Religious and women's studies, not so much.)^

^Second, it may provide a credential that employers want, not because it represents actual skills, but because it's a weeding tool that doesn't produce civil-rights suits as, say, IQ tests might. A four-year college degree, even if its holder acquired no actual skills, at least indicates some ability to show up on time and perform as instructed.^

^And, third, a college degree - at least an elite one - may hook its holder up with a useful social network that can provide jobs and opportunities in the future. (This is more true if it's a degree from Yale than if it's one from Eastern Kentucky, but it's true everywhere to some degree).^

^While an individual might rationally pursue all three of these, only the first one - actual added skills - produces a net benefit for society. The other two are just distributional - about who gets the goodies, not about making more of them.^