Now, many other people wisely do the same. The more people have degrees, the more pressure is applied on those who don't to go get one. Awkward, that.
So, now we have a huge demand for degrees, plus a lot of degree-seekers who (to be honest) aren't really cut out for college. But that's no big deal! The market hears and obeys, as enrollment goes up, standards go down, and bottom-tier schools admit anyone with a pulse. Hooray, everyone's getting educations, isn't this great? Who cares if they're learning anything.
Oh dear, it seems we've stumbled into a Nash equilibrium wherein the competent people are still competent, the incompetent are still incompetent, you can't tell them apart by seeing who has a degree anymore, and now everyone has student loans weighing them down. Alas, game theory, she is a cruel mistress.