“Rare books” usually refers to rare editions of books. Any books out there where there are only a few extent copies of the text itself, are probably not of very much interest or social value, since almost no one is able to read them, by definition.

If you think there is priceless knowledge locked up in books so rare that it is on the verge of being lost forever, then AI labs are not really the problem!

The object itself is the valuable thing, not necessarily the text. Why are so many in the discussion overlooking something so obvious?