I really got into collecting at age 10, which for me was back in 1984, and collecting gives me a sense of nostalgia. Most of the books I buy now are much pricier than anything I could get my hands on back then, but the most fun I had in the hobby was sitting on the floor of a used book store or comic book shop digging through boxes and deciding what books to get with the $5 or $10 that I had with me. Collecting still takes me back to those days.
I don't think the hobby will last forever, necessarily, but neither will I, so it's OK.