buldog5151bass
Kibble, milkbones, and P Basses. And redheads.
You don't own a copy of the book to use as you see fit. You are essentially renting the right to read it on Amazon's service. If they go under, the book vanishes. If they eliminate it from their roster, the book vanishes. There is nothing perpetual about it as everything digital could vanish with the click of a button. So you are only borrowing the right, because it could be rejected at any time. And it is only a right to read their version because you don't have a final, discrete copy of your own.
That's true with anything you get on the net - same with music - you don't own physical recordings. Such is life in our modern world. One more reason to hit up your local library. In most cases, all area libraries are interconnected, so even if your local library doesn't have a book, it can get it quickly. That's how I went through a 10 part series of Harry Turtledove novels.