But I can't think of a way that the bubble could actually pop. Or what it would look like if it did.
Unlike housing, you can't walk away from your education; student loans are designed to prevent debtors from ever escaping their obligations. They're also guaranteed by the federal government, which has seemingly infinite resources.
Educational institutions themselves are also either private, or are state-run, both of which would shield the impacts of a collapse from the average citizen. The average citizen isn't invested in education like they were in public tech companies or housing. It's also impossible to short Harvard or the UC system.
I actually think this is worse in some ways. Bubble pops are scary, but the bandaid comes off quickly. Instead I fear educational indebtedness will just be a silent vampire on our economy for decades to come.