The thing is, book hoarding is extremely dangerous once it gets to a certain point because it's a fire hazard waiting to happen. It seems to often be triggered in people who are living in poverty, and are isolated, so unfortunately they could die from an accident very easily, whether that happens to be a spark from the wrong place, or even a pile of books crushing them.
This is actually a disorder that makes a lot of sense to me. I've definitely felt the urge to be a packrat and our ancestors would definitely have approved of the habit of keeping everything and using everything that was within reach. Anyone who didn't do this would not have survived as well as the next tribe over.
But in a modern world, where even the poorest have a lot of stuff to keep, it can quickly pile up and it's not healthy, especially for mental health.