If I read a book, I usually get rid of it by selling it to a used bookstore, or handing it to somebody else. I buy books that look interesting when I see them, then take them home and shelve them, and promptly forget about them. When I want to read a new book, I browse my shelves the same way I'd browse at a bookstore, except every single book is interesting, or was at once time.
Sure, it's insane, but it's what I like to do.
A side effect is that I occasionally buy the same books several times, either because I want to reread it, or just because I forget that I've bought it already. That doesn't bother me, they all come from used bookstores I want to support anyway.
I have separate shelves for books I don't want to get rid of, like nice editions and heirlooms. But for the most part, almost all the books I own are unread, despite reading being one of the things I do the most.