The conventional wisdom about a college education is that it makes people more productive by augmenting their human capital, and hence they’ll earn more. There’s also a dissenting view that looks with suspicion on the claims about human capital and attributes the higher earnings of those with degrees mainly to credentialism among employers.
Here is a column by a young fellow who entered the Air Force after being schooled at home and is now in college to get his degree. He certainly does not think that college is much of a human capital boost for him. I suspect that many other college students would candidly say much the same thing.