Disney doesn't profit from DVC because it's "more expensive" than paying cash, they profit from DVC because they're locking you in to visiting every year. If they could choose between a cash guest who visits every single year and a DVC guest who visits every single year, the cash guest is more profitable. The problem is, the cash guest can't be locked down.
I have been a DVC member since 2012 and have points at three DVC resorts. Here are a few additional details, from my perspective:
(1) Unlike other timeshares, where the ownership interest is purchased rather than leased, DVC is essentially marketing prepaid vacations. It is a savings if you pay, in full, without financing. However, it seems that many members finance with Disney and I know that members with fair credit have 10-year interest rates of nearly 16%. With a 150 point purchase, 10% down on a major credit card, and the rest financed through Disney, the point cost, with interest, more than doubles over the life of the loan. Therefore, Disney makes money on both the purchase price and loan interest.
(2) It becomes increasingly difficult not to vacation at Walt Disney World. With the number of points I own, any other vacation seems to be costly. Yes, there is still airfare and food, but we have annual passes, Tables in Wonderland, and there is no additional cost for the room because it is booked on points. Last year, I considered booking a trip to Disneyland, but it was hard to justify purchasing passes when we already have annual passes for Walt Disney World. Plus, with Disney's Magical Express, there is no need to rent a car or pay for transportation to the Disneyland Resort.
(3) Now that we visit regularly, we spend more than we did when we casually visited as cash guests. Because we are so familiar with the parks, we regularly pay for upcharge offerings. Since becoming a DVC member, we have gone horseback riding at Fort Wilderness, taken behind the scenes tours, and enjoyed several carriage rides.
Simply put, DVC is a prepaid vacation offering that ensures that Parks and Resorts has vacationers for the next 50 years. The offering is profitable because it generates income through ticketing, merchandise sales, and food and beverage purchases.