I've tried donating to local libraries; they put them straight into their annual book sale. None have ever landed on a library shelf. (Many/most librarians arrogantly insist on buying their own books. "My way or the highway." )
Friends/family who might possibly be interested in same books are like me, if they are interested in reading it, they bought it already.
Unless it's rare/out of print, selling on Ebay or Amazon yeilds pennies at best.
So they pile up.
Now, I only 'read' audio books; with the exception of Graphic Novels, which I get on my Kindle Fire.