Continuing:
Most people think of DVC as a "prepaid" vacation, not as an investment. No one can predict how the value of a timeshare will hold up over the next several decades. Some people have made money selling their contracts, others have broken even, and I'm sure some have lost. But if you're simply looking for a real estate investment, stay away from timeshares in general, even DVC!!!
People buy what they can afford, within the confines of the minimum requirements if they are buying directly from Disney. Once you have bought that minimum contract from Disney, you can add on in increments of 25 points (50 if you finance, I believe.) People do different things. Some buy one contract and then add another at a different resort (there are options to book early depending on your ownership, but that's a graduate level question and I think we're in the early learning curve stage here!!!)
Once you are "paid up", there are no more associated costs with the trip itself, like room taxes or anything like that, but there are membership dues each year. This is consistent with many timeshare locations. The dues average about $4.00 per point, so 150 points would be $600.00 per year.
I think the issue of other vacations is personal for everyone. Some take multiple vacations outside Disney, and some only take their DVC trips. We go other places in the years when we can afford to do so, but we know that we'll always have a week at BCV and a week at HH!!!!!
Oh, and the contracts last until 2042, except for Saratoga Springs, which lasts until 2054. So they are not "forever" but do manage to suit most people who are in early or middle adulthood now - they'll stretch for the lifetime of your vacations and get your children into their thirties or forties as well, so your grandchildren can get to see WDW!!!!
As tot he number of points, I have two contracts of 165 points each. That's enough for a two BR villa at Hilton head in the high summer season for five nights, or for four nights at the BCV, with a few left over. Points are assigned depending on time of year, season, and size of unit (studio, 1,2 or 3 BR villa.) So look at the top of the page from the DVC board and you'll be able to look at BWV point requirements for next year.
Whew!!! That's all I can think of!!!!