Well I consider the money they make on all of the other things (food, merch, tours, tickets) to be part of the DVC revenue. DVC locks people in to taking their vacations at a Disney owned property (WDW, DL, Cruise, Adventures). Clearly they like the value proposition or they wouldn't keep making DVC resorts or converting units.
If you want a direct points to profit exchange after contract close then I would again mention the expired/unused that happen every year. Disney still has the points sold but can allow others to book the room instead - thus profiting twice on any unused but previously sold points.
You could also point to the fact that they advertise exchanging points for cruises and
Nat Geo adventures. They market those options as good alternatives to staying onsite, offering flexibility, but if you have ever read about the exchange rates or done research on it then you will know that in most cases (and certainly in the case of a direct buy situation) the guest is on the losing end of those exchanges. The DVC point to cruise exchange is a clear profit line for them.