I think the break even point is harder to figure out than most think for several reasons:
1) Many use rack rates to determine it, yet odds are they wouldn't have been paying rack rates....unless they are as foolish as I was before buying DVC (I never shopped the best price).
2) Many people finance and don't take the interest into account.
3) How many REALLY would have gone to Disney this often had they not bought DVC? Odds are I would have gone every other year while my kids were young, but I have no clue how often I would have gone later in life. Now I am locked into Disney. I don't mind that, but that changes things in terms of break even for me, as odds are that other hotels and companies would have gotten more of my vacation dollars had I not bought DVC.
4) For those who have the initial outlay sitting in a bank account, they have to consider the interest that money would have earned had they just left it in the bank and paid cash for their vacations (considering interest when determining the profit).
5) Last but not least, the break even time period changes depending on whether you would have stayed in a deluxe, moderate or value resort. Many DVC owners jumped from value to DVC, and who knows what their hotel choice would have been had they not joined DVC, or how frequently they would have gone to Disney World. The purchase of DVC makes much better sense for the person who always stayed at the Grand Floridian over the person who always stayed at the Pop Century during free dining.
I am excited to have DVC, but I am not quite ready to declare it a financial victory for me yet. For starters, I financed it through a home equity loan (piggybacked it on some other things we were doing around the house). Second, I was perfectly happy in moderate resorts. I probably could have stayed in POR forever (I love that place!). Third, although Disney will always be a special place to my wife and I, there probably would have been 3 or 4 year time periods that didn't involve a Disney trip (later in life) had we not purchased DVC. That last point is why I hope Disney builds as many timeshare hotels around the globe as possible, as well as why I hope Disney's trading power with RCI improves.