Do you know what the cost of a night at a
DVC resort will cost 35 years from now? Of course not.
For the $15/point, like DVC in itself you are locking in the maximum you will pay - just an insurance policy. You have no idea if the payoff will have made sense financially until it comes time to use it.
For the $2250 (yes, in today's dollars) we've guaranteed that our future costs will be no more than the then current annual maintenance. Neither you, nor anyone else knows today what a night in a DVC property will cost in 35 years (though I'd say there's a very high probablility it will be significantly higher than it is today). We've guaranteed that we have no other future costs to DVC other than maintenance. In our case, the $2250 is a small price to pay for the guarantee that provides. For some people with 1000 points or more, it is really a financial decision today - that they can't or don't want to come up with an extra $15,000+ today or finance that kind of money. For these people, the "alternative investment" reasoning doesn't work - because they aren't going to set that money aside or don't have it anyway.
We had the money available, have absolutely no risk that if it were "invested" whether it would keep up with inflation or the price of points going forward.
If you can justify buying an insurance policy, this is really no different. Those who don't buy have the unknown risk, those who do buy have no risk. Simple as that.
Everyone in "the gang" can toss around all the reasons why it makes no sense financially and throw stones at the $15/point today...however, that doesn't mean they are correct. Whether the price were $10 or $15 makes little difference in my mind. $750 difference in our case - not going to break the bank. Would a lower price have been nice - of course. No need to argue whether it is the right move financially or not - we're done and are guaranteed our 50 years.