Mostly I loan them out and never see them again. But once I lost my entire collection of Vampire: The Masequerade books in an unusual incident - they were soaked in jet fuel and ruined. I was serving a tour of duty aboard the USS Kitty Hawk in '94, and I loaned my entire collection of Vampire books to a friend who wanted to GM a game. Well, he was a jet fuel airman and a JP5 line ran through his bunkroom. One night the line burst and the entire space flooded with JP5. He slept on the bottom bunk and my books, of course, were on the floor next to his rack. All dozen of them. Thankfully no one was hurt, but I lost about 200 bucks' worth of stuff.