Typically, at an assumed long term return on invested free cash of 7% per year, buying into
DVC vs. Renting points pays off between 16 and 19 years depending on the resort, the points chart etc. At current prices, VGC never pays off. You could rent every year, invest the money not spent on buy-in, and come out a fair amount ahead. (this is all assuming fee increase matches average inflation). The only thing you get now if you buy is the 11-month window, but even renting you can get that.
That being said, availability is so scarce that you probably couldn't get a spot if you tried to rent every year. It has a life of its own at this point.