I found this comment on Hacker News to be spot-on:

The complaint lays out in steps why the plaintiffs believe the datasets have illicit origins — in a Meta paper detailing LLaMA, the company points to sources for its training datasets, one of which is called ThePile, which was assembled by a company called EleutherAI. ThePile, the complaint points out, was described in an EleutherAI paper as being put together from “a copy of the contents of the Bibliotik private tracker.” Bibliotik and the other “shadow libraries” listed, says the lawsuit, are “flagrantly illegal.”

This is the makers of AI explicitly saying that they did use copyrighted works from a book piracy website. If you downloaded a book from that website, you would be sued and found guilty of infringement. If you downloaded all of them, you would be liable for many billions of dollars in damages.