Mind that '4 year college' includes a lot of places that are outside of what you may be thinking of. U. of Phoenix is an example that is very predatory in their loans. Also, many bible and other religious colleges may be included and there are a lot more of those that you'd think. The reasons for dropping out are also complicated: Having a baby, family health problems, personal health issues, mental health, debt from other sources, plain not wanting to continue anymore, drinking or smoking in the dorms, getting engaged (at BYU they say 'ring by spring or your money back') , etc. As with any population, there are a lot of circumstances. Still, I agree with you, the debt incurred here is unsustainable, especially as employers see a degree as a basic test for employment more so.