This is the "poor people have refrigerators" thinking writ large. Tuition and room and board can easily crack $100k at the schools that are social gatekeepers for the upper class (that people want to go to for that reason).
> When I asked my stepson, who graduated last winter, if he knew of kids using their student loans for non-school-related purchases
Might as well ask your stepson if he knew anyone doing drugs instead of going to class. It's a drug pandemic! Do you know anyone who has cheated on a test? It's a cheating pandemic! Do you know anyone that sleeps around? Promiscuousness pandemic!
People love to gossip, and they love telling stories about outliers. Asking directly for stories that stand out is about the worst kind of "informal" research you can get.