I hadn't even thought that this might increase the likelihood of books being thrown away. Like you, I like to keep my books. Still, there was a time when I had more time for reading and not a whole lot of money and despite frequent trips to the library I also did a lot of book trading, because there was a store that would let me take home a used book for every two of the same price that I brought in. (That model hasn't been economically viable for a while.)