Fair use is any copying of copyrighted material done for a limited and "transformative" purpose, such as to comment upon, criticize, or parody a copyrighted work.
Yes, it's a list of quite similar ways of commenting upon a work. Please explain how training an LLM is like any of those things, and thus, how Fair use would apply.
I'm not saying that training an LLM is like any of those things. I'm saying it doesn't have to be like those things in order for it to still be fair use.
The use of the material to create a commercial product as well as the reality being that the humans training it never buy the data on an individual level.
The training argument is probably going to come up dry by the time the court works its way through expert testimony, as the underlying argument for training as infringement is insane.
But where OpenAI is probably in hot water is that torrenting 100k books in the first place runs afoul of existing copyright legislation.
Everyone is debating the training in these suits, but the real meat and potatoes is going to be the initial infringement of obtaining the books, not how they were subsequently used.