I'm not the author but here's my answer: I get zero books from the Kindle store because of DRM. I want the book to be mine and be able to read it as I please forever. I considered buying DRMed books and remove the protection. I never did and this is getting difficult or impossible due to better crypto (but it can't defeat OCR). There are plenty of books to read with no DRM on them, or just buy paper.

To answer the OP, I can't be sure but creating an ebook takes time. Try doing it with Calibre, it's an interesting exercise. Easy for text novels, not so much for books with many pictures, formulas, tables, footnotes.