But there is so many books there that no one want's to read. Hundreds of the same book lying there for months or years.

Same for public book-sharing "libraries" (small shelves that look like bird house, usually in parks etc). People really like them and there are many in my city, but most books there are products of a gone era and a gone mindset. No one want's that even for free.

We were taught respect for books, but not everything is worth preserving.

I'm in the camp that perhaps it's healthy to not grasp onto every bit of information. that some artifacts dying a natural death is maybe just the way things are

Speaking from experience, the information density of published books is a lot higher than most internet text. It's very high quality training data.

The goal here is to have all human knowledge in a single file, which is pretty neat IMO.

They're scanning millions of books.

It's the diversity of text that helps. One of the lessons we've learned is that more training data leads to better models. Even old books have different mixes of word sequences that will improve the model. The returns are diminishing, but when you have the pipeline set up to ingest it you might as well keep adding to the dataset.

LOL, not being rude: have you ever read a book outside of what they forced you to read in school? Most old books are not O'reilly's manuals for Visual Studio 2014, they don't go out of date.

They are interesting to human beings for the same reason they are interesting to the labs. If it was just about quantity of text then the labs could generate text with the prev. gen model and use that alone to scale to the next model, there is something of immeasurable value contained in books (hint: it starts with an i and rhymes with bin formation).