I have a perspective not yet shared. My DW and I love traveling and before kids would go somewhere every 3-4 months. 6 years later, and as life gets busier and busier, without DVC we might never take a vacation. Literally, as DVC will tell you, this was an investment in FUTURE vacationing for our family. Now, whether we like it or not, we have vacation plans 7-11 months from now. And next year, dangnabbit, we WILL go on vacation and LIKE IT! It is so comforting for us and (now) our two kids, to KNOW that there is a fantastic vacation in our not-too-distant future. Before DVC, we had to watch for deals (which is like clipping coupons, which I hate), go last-minute, and feel like someone else was always getting a better deal than us. Now, we know we got a great deal on really luxurious accomodations.
We NEVER would have spent the $1000+/night on a 2br ocean view suite in Hawaii.... We never would have afforded it. But, amortizing our buy-in and MF's, that suite for the week at Aulani "cost" about $2k. AND we took our in-laws and treated them! Nothing is better than impressing the in-laws (that was worth the buy-in right there). Same thing at VGC before Christmas last year: I called CR for a regular room (too small for us) and was quoted over $300 for ONE night! Then, just for kicks, I asked about a 1-br suite... Over $1000! Yikes! We wait-listed for a 1-br villa and got it. A total splurge we couldn't have afforded otherwise. And we made one of our favorite family memories thanks to DVC. And now it's an annual tradition.
Any time share is not an investment in the classic sense of the word. But I think most people here and at other TS's will tell you that no matter the high MF's, the planning ahead, and all of the other stuff that comes along, the "investment" is in future (and past) family times that you will be FORCED to spend together... And you WILL go on vacation dangit, and you WILL be forced to have a good time... And that's an investment I'll make every time.