I think this is a duplicate of a story that ran on the front page yesterday:

https://news.ycombinator.com/item?id=49383026

The big thing here is: libraries and the book trade destroy millions of books every year. If you clean your attic out, box up all your old books, and bring them to your local library donation box, they'll quickly sort through it for things that might actually circulate, and the rest go right to the recycling center.

A lot of people in these comment threads seem not to understand that destruction is part of the natural lifecycle of a book. Books generally don't get preserved.

And then there's the problem that the original reporting that kicked all this off, at 404, is specific about what is meant by "rare books". It's not, as they say, first editions of Oliver Twist. Rather, these are books nobody cares about; that's what makes them rare in the first place. Vanity press stuff, or manuals for old equipment that isn't produced anymore. All these books would naturally end up a dumpster.