I have talked to a Japanese professor about this. It is theoretically possible to use GPT or similar generative models to create a novel tailored to a single person and sell it to them.

Of course, some editing might be necessary. The dangerous aspect we are thinking? What if we can make an entire visual novel and lock that person in a perpetual loop of self-gratification? Pay more to unlock more chapters? Pay even more to unlock a specific route? Pay even even more to add a new love interest?

It is completely messed up, but sometimes we have this kind of Black Mirror talk as a thought experiment.