You’re right. My daughter sent me pictures of the dumpster at her college campus apartment when school let out last summer. Stacks of furniture and rugs. The amount of nice furniture was shocking.
I used to live across the alley from a near-campus apartment complex. Students would dump EVERYTHING at the end of spring semester. I still have a few kitchen items from those dumpsters. There was a guy who lived not far away who used to dumpster-dive the whole neighborhood and have yard sales every so often; I think it was a significant part of his income.
Never, and I mean never, take used furniture from college dorms. Especially mattresses.