Most Americans want a college education, but it is expensive. On average, a four-year school costs about $25,000 per year, or $100,000 for a degree. That’s roughly half the median house price – a substantial investment. If you have to borrow to finance a college education – just like you borrow to own a house – is it really worth it?

The answer is yes for most people. But the outcome is not free of risk, especially for those students who borrow heavily relative to their future income prospects....