My family (specifically my dad) owns both a beach condo (3 hrs away) and 430
DVC points (plus 4 Marriott weeks).
He and my mom bought the condo back in the '70s when my sibs and I were all gradeschool kids. It was great then since we always had a place for summer vacation. My mom would stay at the beach with us kids and my dad would commute home for work. I think we averaged about 3-4 weeks of the year.
Then it became a weekend getaway for my parents once my sibs and I grew up and started going our own ways. Now it's become the summer vacation spot for my sibs and their gradeschool kids. But for my dad?
Well since buying timeshares, he's averaged 1 weekend a year in the place. When he's home, he likes to be home. And when he travels, he enjoys going off-season to warmer climates. (The beach here is really only pleasant 4 months of the year.) With his timeshares he can manage 8 to 12 weeks or more a year. He splits it up with a two week trip every couple months.
The place has made a very nice real estate investment for him though. But it costs him around $10k a year just to do the most minimal upkeep (fees, taxes, utilities). When he's had to update the furnishings and do other refurbishment, you're talking another $10k or more. And then it's a pain to have to keep track of who's using it and what needs fixing. He's put a lot of elbow grease into the place over the years.
I think he pretty much holds onto the place for my sibs (they couldn't afford the beach otherwise), investment value and sentimental reasons. (My mom decorated the place with lots of family trophies and photos.)
Based on that example, I think it really only makes sense to invest in a second vacation home as an investment. If you truly think you'll get at least a weekend a month or more out of the place, then that makes it worthwhile. Otherwise, timeshare ownership in a good program gives you more bang for the buck than most places.