[huherto]

"Should a bank really be making $100,000 unsecured loans to 18-22 yo-s just because someone in their (future) field has the potential to repay it?"

It is should be like insured deposit in a bank. The government guarantees up to $100k or so, but if you have more you run the risk your self. In this case if the banks lends more than let's say 40K, then they are on their own if borrower declares bankruptcy. (I may not be using the proper terminology. English is my second language)