When we joined DVC in 1993, we had usually stayed in either townhouses at Disney Village or Deluxe resorts on most of our trips. I tracked our DVC expenses (purchase price, maintenance fees), benefits (discounts we would otherwise NOT have gotten- and free admission tickets for 6 years) and compared those costs to what we would have spent for the accommodations we usually reserved in the past. I even amortized lost interest on the purchase price.
On our original purchase of 230 points we had reached a "break-even" in just under 4 years. We have added on 7 times since then as well as purchasing 3 resales and I lost interest in tracking our expenses since I had satisfied my curiosity that DVC was a "good deal" for our family.
Having said that, I do agree that whether DVC "pays for itself" will vary greatly depending on how each owner chooses to use the program. The "costs" will vary greatly for those who choose to use DVC points for the cruise, to stay at non-DVC resorts, to stay at DVC resorts on weekends or during higher point times of the year. I'm satisfied that DVC is a "good deal" even when using points for those options just based on the cost of the maintenance fees.
I find the flexibility of DVC to be the foundation of the program. Since we can choose when we want to go, how often we want to go, what resort we'd like, what villa-type we want and what other option we'd like to try - the only real limitation is the number of points we have access to at any given time. Even banking/borrowing enhances the flexibility of the program.
I think at times we tend to oversimplify and overstate the economic "value" of DVC and interject the way it makes us feel - and that emotional value is also a valid component of DVC ownership (and it is not an accidental component, IMO

).
Bottom line is that for most of us, DVC does pay for itself - if not financially, then certainly emotionally.
