You can buy books on Amazon and use them on a Kindle device or app for a fraction of the price of a hardback or paperback.
I’ve bought lots of books for $.99 through it.
In the late '60s, I found a bunch of 99 cents bookstores in the West Village ( Greenwich Village, in NYC ) and stocked up on quite a lot of books and even more first eds. :-)
Unlike buying books for use on a Kindle, my books increased in value and I get to own these hard copies, without the worry of them ever being taken away, have words or whole sections removed from them. And I don't want to read a book on a machine.
Each to his own! :-)