This blew my mind but it’s so obvious now that you mention it. If you already have a commercial advertising enterprise set up, you can transfer in for $12-18 and then rent out above $20-30. Especially as Member Services is sometimes willing to help you swap out pristine (bankable) points for more distressed (expiring soon) points on your reservations, so you could probably spec book rooms, buy distressed points to backfill them even cheaper, and then use your points for a new reservation and repeat.
I’m not sure I think it’s a deliberate dragnet operation, but on the other hand, DVC can trace the exact points transferred in to a reservation, which is not made in the name of the owner, and it would be a pretty red hot trail that they acquired the points just to rent them out (commercial activity) as opposed to saying it just happened to be extra points or an existing reservation you couldn’t use.