As an accountant for 30 years, the one thing I have learned is that 10 people can be given the same numbers and come up with 10 different answers..it all depends on your perspective and what you want the numbers to come out to.
Your example is an extreme example of the power of positive thinking...my quess it you are a
DVC member or you want to be and you are trying to justify your purchase (or expected purchase) and there is nothing wrong with that.
A financial advisor armed with his HP12c will run present value and future value calculations and show you how you can do better inventing in pork bellies over the next 35 years...and maybe he will be right...but at the end of the 35 years, will you be happier having invested in pork bellies or DVC ? ... depends upon what you want.
The decision about buying into DVC should not be about whether or not you are making money or losing money...it should be about your philosphy of how you want to vacation and live your life...if you are not into the "Disney" thing, then DVC is probably not your bag. When I told my co-workers that the DW and I were going to WL for 5 days sans kids, most of them looked at me with a puzzled look and said..."why"...well, if you have to ask "why" then you don't get it.