When I started my career in technical support, the people I admired the most had the most information. Their years of experience, context, and intuition were inspiring, so of course, throughout my career, I wanted to emulate those well-informed individuals. I no longer need esoteric technical knowledge to that degree. Why hold onto most of it? I would only read passages on occasion, anyways. Best to keep one or two references then donate the rest.
When I moved furniture for minimal wage, we estimated the two densest things to move: textiles, then books. Bundles of rolled-up carpet were only beat by furniture. Large boxes of books might not seem bad until you have to move it a few times or the fatigue kicks in. All the boxes I’m using for books are smaller than around 12″ width, 12″ height, and 12″ depth. You never know who’ll give you a hand. Strong or otherwise.
Let’s say you donate three books to your local thrift store: a book that is waterlogged, a book that is overly common, and a book that is innocently quite valuable. What happens to these three little books? The waterlogged book will most likely in the trash compactor or recycling bin. The valuable book will end up in the store. But how about that 10th copy of a book the thrift store has that hasn’t sold?