A person can only service a few projects a year and it takes day or weeks on ingest new knowledge. A trained network only needs to train once and faster than a person, it can then be replicated and is only limited by computing power.
That skews the market and the value of the books. I would not write a book if it was then ingested by and AI and never sold to a person.
For example, if a college professor reads a book, and then uses the knowledge gained to teach, that reduces the value of the book (assuming the professor doesn't then use the book as the textbook for a course).