We analyzed 14,419 self‑published genre‑fiction books sold on Amazon from 2023 to 2026, using full‑text AI detection to identify those with >25% AI‑produced content.

Although AI books represent a large share of the catalog, they account for a smaller share of sales. Over the period, quarterly sales grew 19.2‑fold, while revenue rose only 8.9‑fold, causing a decline in revenue per selling book across most genres.

AI books are gaining a growing share of top‑rank positions, especially in genres with high AI diffusion and where Kindle Unlimited is available. They also draw more distinctive language from existing works, with overlap increasing as revenue rises.

Thus, generative AI reshapes the creative market through scale rather than quality, raising important questions for the fair‑use defense in copyright disputes.