"Once again, it's the mismatch between the debt and the borrower's income, their ability to repay," Calhoun says. This time around it's the government making the vast majority of the loans. That's effectively turned the Department of Education into the country's largest consumer lender. And, Calhoun says, more and more people can't pay. "Already in the student loan world, we are seeing default levels that approach what there was in the subprime mortgage world," he says.
https://www.npr.org/2019/12/09/785527874/student-loans-a-lot-like-the-subprime-mortgage-debacle-watchdog-says
