THE IDEA DIFFUSES. I claim there's a subprime sector in higher education. Econ Log's Bryan Caplan comes to a similar conclusion.

[M]any "investments" in education end in foreclosure - also known as "dropping out".

He extends the argument.

If the rate of return for a completed year of education is 10%, but 6% of students who start a year don’t finish (and waste a year of their lives plus tuition), the expected rate of return is only 3.4%!

The economics is straightforward.