The quacks I have met are often quite sincere. So I'm not interested in awareness that the behavior is bad, just that the behavior is a net systemic negative.

I agree there are differences between what this guy did and mortgage brokers. In particular, this guy is shamelessly and consciously exploiting others to his profit. Some mortgage industry people were like that, but many others really thought they were doing something good, or at least didn't think very hard. They were wrong, though.

This guy was of course a net negative on the whole system. Imagine that no money ever changed hands. What happened? A guy spent 2 days driving back and forth between two rental car companies. Other people spent time filling out pointless paperwork. Gasoline was burned. Wear and tear was put on the car. Substantial costs for no intrinsic benefit.

If the guy had just gone into the Avis branch nearest his house and stolen $3k from their office safe, everybody would have been better off. That one happens to be currently legal and the other currently not doesn't change the wastefulness of it.