Dave,
I have to respectfully disagree. If you pay cash for your points (as you should), then it does not matter what the "value" of that $17k is in 50 years (and would be impossible to predict), since you have already spent the money. What matters is the dues that you pay each year. For us, we own 360 points, and adding in the 3-4 percent average yearly increase in dues ( we own at SSR, and ours are only going up 1.73 percent this year!), with the initial cost, we came up with an approx. cost of $6.35 per point over the life of our ownership. Well below the normal rental price. Even if dues go up more a few years from now, we will still be below the average $10 rental price now, and that is destined to go up over time as well. It will not stay the same over the next 20 years either.
You can "what if" the purchase to death, but the fact is, it is a luxury purchase (like buying a boat or a sports car that you don't really need) that is up to each individual to decide on. If you prefer sailing on the open seas, a luxury boat makes more sense. If you enjoy going to Disney as much as we do, it can be a big money saver.
For us, we go multiple times per year, and it is worth every penny we spend on it. We have already gone well past the break even point (even taking 40 percent discounts into account), and we are saving a ton. We are taking 2 trips in the next 3 months that would have cost us over $5000 (even with a 30 percent discount) for our rooms, and yet we are paying less than $1700! Add in the $300 PAP savings each - $600 total, and you can see why we love DVC!!! Our savings on rooms and park tickets these 2 trips alone is almost $4000, and we will book at least one more trip for next year to use our passes on, adding even more room savings as well.
Anyway, DVC, I will absolutely agree, is not for everyone. All situations are different, and it just works for us. It will NOT work for everyone.
Kevin