Do folks who mainly do Disney cruises not have DVC membership?
To use points on a cruise you must by direct. That said, the exchange you get to use those points is a TERRIBLE value! If anything you would want to rent out your points and use what you get from renting the points to go on the cruise paying cash.
My best advice is to go on
YouTube and search for Jen Lefforge. She has several videos on buying DVC that I found very useful. If you are still "in" after watching those videos, write a spreadsheet comparing the cost of DVC vs. the cost of where you would typically stay. If that's a Moderate or Value resort, that's the comparison you want to make, NOT a Deluxe if you wouldn't ordinarily stay there. Figure in a regular rate of inflation for the DVC maintenance fees and a higher "Disney Inflation Rate" for the rack rate on the room you are comparing it to. You should be able to calculate a guess on a "break even" that way, then decide if you are comfortable with that.
In the mean time, also peruse the many threads here about DVC so you understand the 7 vs 11 month booking windows, banking vs. borrowing points, the differences between the resorts, use year, renting points, blue card "perks" you only get buying direct, etc, etc, etc. If you cannot answer questions at length about these many DVC nuances, you have not researched it enough. The last thing you want to do is make the leap, then be caught with points you can't use, muttering, "but I didn't know..."
Best tool I've found is the "DVC Calculator" phone app - excellent for answering those "what if" questions about how many points you need.
And so much more. Is it right for you? I wouldn't know until you do.