A reason why authors SHOULDN'T sign up for ChatGPT plus accounts:

If OpenAI's billing DB leaks, and your name is in it ...

People will start questioning whether you actually wrote your books, or used a mechanical ghostwriter.

US case law denies copyright protection to AI-generated material.

Your publishing contracts typically include an assertion of sole authorship by you.

So if it looks possible that you used ChatGPT, you might end up pissing off your publisher and/or losing a book deal.