You give a book away today. Tomorrow you are looking for a quote from it (or a paragraph).
And if you have many books in Spanish (as I do) published in Buenos Aires, they fall apart within months. Most are Borges. I would not throw them away.
I recently got rid of 1000 books. I found it much more stressful to find homes for them in used books stores, public libraries and friends and less so to just dump them.