The power of patina.
Being a visual person, the visuals of the printed text on paper is important to me. I don't read digitally. I buy fewer books, but probably spent about the same as you. I see my books as my contact with the authors. We are having a conversation. I also remember selections based on where they were placed on the page. Twice during my life I have purged my collection. It is one of my few regrets. I also have this notion that some day, the internet will go away. So, my physical collection may have value as the seed bed for the recovery of civilization if ever the apocalypse comes.