Shouldn't have "bought" them in the first place. Buy physical books, or DRM-free books on sites like gumroad, or just pirate. Don't give in to the rent seeking business of pretending to sell you what you can't own. If you like your Kindle device, you can use KOReader to read epubs and reduce dependence on Amazon. If I sue the bookstore, they can't just take all the books away, but if you dispute a charge with Amazon, they'll do it because the ToS says they can. At the very least, try downloading and de-DRMing all the books you received from them: https://github.com/noDRM/DeDRM_tools