This is not an anti-Kindle rant. I have purchased (rented?) several Kindle titles myself.
However, YSK that you are only licensing access to the book from Amazon, you don’t own it like a physical book.
There have been cases where Amazon deletes a title from all devices. (Ironically, one version of “1984” was one such title).
https://www.nytimes.com/2009/07/18/technology/companies/18amazon.html
There have also been cases where a customer violated Amazon’s terms of service and lost access to all of their Kindle e-books. Amazon has all the power in this relationship. They can and do change the rules on us lowly peasants from time to time.
Here are the terms of use:
https://www.amazon.com/gp/help/customer/display.html?nodeId=201014950
Note, there are indeed ways to download your books and import them into something like Calibre (and remove the DRM from the books). If you do some web searches (and/or search YouTube) you can probably figure it out.
Oh, so it’s like a sideloaded Kindle app?
Yes exactly! On Kindles to install that app we need a jailbreak (and the procedure will depend on device and firmware version, since we are trying to circumvent Amazon limits), most of the OS stays the same and you can still use the normal “reader” app.
Of course if you are already satisfied by the normal reader all you need to do to gain more freedom is managing your books with Calibre on a computer, it’ll take care of converting to kindle format if you put an epub in it, and send it to device, with just one click. My dad does this after I showed him once or twice and he’s not techy at all.