Perhaps you're a hoarder. Perhaps you're keeping them there until you can give them away as a birthday present to someone you don't particularly care for. Whatever the reason behind your accumulation of abandoned books, there's always someone somewhere else in the world that could be reading and loving those books that you use as a door stop.
And even if you don't feel like giving those books to a library and being a wonderful human being, there's always other ways of recycling these literary orphans...
How about this recycled book chandelier by Lula Dot Studio?
Maybe turn them into pot plants, like Italian designer GartenKulter.
But perhaps the best of all, a recycled book library information desk! Brilliance!