I've never tried it myself since while I enjoy writing, I've never published anything in recent times. However, I have seen people give demonstrations of AI's current-tech ability to craft a story, and to be honest, I don't know how it could be selling. Maybe the AI models i witnessed were low-quality, and perhaps the ones others use are much more advanced...but as it is now, AI still isn't skilled enough to write an entire story.
From my experience, it always breaks down after a few thousand words, and sentence structure, grammar quality, and just general creativeness begins nose-diving after around 3k-4k words. AI could probably do small chapters.....but that's about it. It has this habit of turning paragraphs into choppy, one-sentence bars that are so jarring and abruptly ended. I can't really explain it properly.