This is why I've stopped buying books on kindle. It gives Amazon the power to censor your book library, and it would not surprise me at all if we see them exercise that power soon.
I personally find a rip of the book online to drop onto my reMarkable then purchase it through some ebook marketplace. Now I have a DRM-free copy and the author gets their cut.
That's certainly noble, but it doesn't send the message that you're unhappy with DRM. You're ultimately engaging in piracy and at the same time not voting with your wallet.
I don't see any alternative, but just wanted to make that point.
Whenever I buy an ebook I go through the painful process of downloading it to my laptop either directly from the store (e.g. Kobo) or via Calibre [0] if I bought it from Amazon which I try to avoid, removing DRM via some tool I found somewhere and uploading it to the ebook again via Calibre. It's annoying an probably illegal but no one can take my ebooks away that way.
I'm pretty sure the kindle DRM is broken easier than that, DeDRM came up on my quick search, but flipping through the book to copy all the pages is an easily scriptable task.
They have pulled books before I believe. However there are many good drm free ebooks. I still use a Kindle because I like the device but I keep it in airplane mode nearly all the time and copies of drm free books on my pc.
Edit: I manage my library with calibre and the device plugged in. You never have to take it off airplane and it gets better battery life.
Amazon banned me (for something completely unrelated to Kindle books), and I lost access to everything on Kindle as a result. It's a good thing I hadn't spent much money there, and obviously I'm not buying any ebooks going forward.
Buy ebooks from Baen directly, or from Tor on your service of choice. These publishers release books DRM free, so you actually own the file. Any other ebooks you “buy”, you’re renting.
I actually really don’t care about kindle because it’s only useful for certain formats I tend not to keep anyway and is a lot more convenient and cheaper than hunting down physical copies of stuff.
I originally had over 200 books, all read, gathering dust so I gave them away. They took up space and attention and were a pain in the ass when I had to move house.
As for the convenience, I do a lot of hiking and it’s not much fun dragging two books from the expanse series with you versus a kindle in a ziplock bag.
I have physical copies and PDFs for technical books and reference material though. And a lot of text files.