It's been my observation that there are a lot of obsessive personalities playing RPG's, mine included. Now that I'm in my upper mid 30's I find that my income has increased to the point that it has fed my obsession with RPG's to an unhealthy level. I've posted in a few other threads and hinted at having a large collection. I have well over 200 3.0 hardbacks, and literally thousands of over RPG books and materials collected over a span of 26 years of gaming. I don'te ever rid myself of ANY rpg products I've purchased intentionally.
I run games, and I've received a lot of posititve reinforcement from my friends whom I game with over the years, which has certainly fed my love for storytelling... and consequentially reinformced my obsession with RPG collecting. There are some games I've collected just because I enjoy reading them, such as Rifts (great game setting, abysmal system), and Forgotten Realms. Currently the only game I collect and don't play is the Midnight Campiagn setting, its beautifully written.
I purchase GURPS material because I personally feel the GUPRS worldbooks and particuarly the historical books are brilliant, and I prefer the GURPS system to D20, though currently I'm only running D20 fantasy games (on in Forgotten Reals, the other in Kalamar - another brilliant setting).
After 26 years of gaming, I adore sitting at my desk in my game room and looking over at my five book cases of games and just remembering the thousands of hours of great gaming memories that rest upon them. Some people watch fish to relax, I lay out on one of the couches in here and read game books.
Edit: I'm scaling back my RPG purchases now. This last month I invested over $200 in rpg books and when I balanced my accounts I realized that this money is much better spent elsewhere. At what point is enough.. well, enough?