What you're describing here is actually a much more broad problem in the book industry, in my opinion. Almost every book written today is written with only one goal in mind, selling as many copies as possible.
People don't have to use LLMs (they don't seem to be AI yet) because they can simply choose not to. For authors, write books that you want to write because you believe you have a story to tell. Worry about perfecting your stories and enjoy the process of writing, don't be an author just for the sales. Once you peek behind the curtain and learn the economics of the book industry, you'll realize there's very little opportunity for making enough cash to even worry about shotgunning a mountain of LLM books into the world anyway.
Read that last sentence and tell you think that’s reasonable and likely to happen?