You are asking all the right questions! The reasons people decide to own are probably as varied as the owners. I actually believe that for most people, renting timeshares from the owners IS the best strategy. Owning a TS means that you are responsible for paying the Maintenance Fees annually, whether you use it or not. And should your lifestyle change, you may not be able to get out of the ownership as quickly as you would like. There is a vibrant rental market for these properties, and the costs are probably lower than owning, so it often doesn't make sense.
I PM'd with Gina many times before they purchased, and made these same arguments, but alas she and Steve made the decision to buy not just one, but two units - so I guess my arguments aren't very convincing.
We have a couple of personal reasons for owning, not the least of which is my work. I do contract based project management, and I don't get paid holidays. So before owning a TS, I didn't take holidays. Just taking a week off work costs me a bunch of $$$ without even booking anything. Now that I have paid my maintenance fees already, I feel that I have to take a vacation. And that's just good for me and the whole family.
We specifically like SVR because we love Orlando, year after year. And it is amazing to "come home" to our little piece of paradise each time we return; Vistana is a place that has the vacation vibe and amenities we want. We own a deeded week ownership, so we know exactly which unit we will be in if we use our own ownership week, and that is very special. We may only own 1/52nd of that villa, but it is ours! We have stayed in quiet a few other TS properties across the US and Mexico, and have yet to stay in any other that makes us regret this purchase.
If you do decide to take the plunge, a few words of advice:
1. Get educated - spend several weeks getting to know the community at TUG
www.tug2.net. The TS owners there will open your eyes to world of possibilities in how/when/where to own/use/rent your interest (and a lot of them will advise you to just rent)
2. Buy resale - those units you see on ebay for $1 are real. The really good ones do command a bit of money, but for the most part, they aren't worth anything. You just have to remember that your $1 buys you a $1000 dollar a year commitment
3. Learn to use your ownership - we leverage our two ownerships into two or more trips a year for us, and have plenty leftover to gift or rent to family and friends. We may even come close to breaking even this year (effectively making our usage free).