I'll never understand people that would rather have something rot than just part ways with it and let it go to a good home.
Same here, however a friend of mine does own a 69 Camaro that his dad gave him before he was 15. Car is in a mess and needs a total restore. He's had offers to buy it but he doesn't want to sell b/c he feels he'll never get to own another one. However it continues to sit b/c he has no money to fix it, and he has no money to fix it b/c he works low dollar paying jobs whenever he feels like working.
I'd guess other reasons for not selling are if someone's owned it for so long and they have too many memories and such it's as if the car is family. But OTOH if you're going to let it sit, you might as well let someone else have it who can/will fix it/drive it.