Student loans are the only legal way to sell yourself into "debt slavery"[0] in the United States. It's not the 17 year olds that are screwing up, it's society as a whole by even allowing this situation to exist.
At that point, the incentives of schools and the incentives of students would be aligned. Schools would not lend huge sums to students unless they had confidence that the education those students got was adequate to prepare them to repay. And the situation would fix itself. The fixed situation would probably have a lot fewer humanities students, and those students would have better job prospects since supply and demand would be aligned. Degrees would be shorter and less expensive, and overheads would be lower.
I think doing that would likely result in no loans for many students or at least higher interest rates. Hell, if I were 22 with $100K in student loan debt to be discharged, I'd be silly not to declare bankruptcy.
Do you mean that student loans are the only legal way to attain a loan whose collateral is your future earnings potential? Because if so that's very wrong.