I too once had a ginormous library. But I realized that I would never read about 90% of my novels and other books again.
So I got rid of them. Kept the ones that I do look at again.
But I got rid of encyclopedias and dictionaries. They took up way too much space, and with the internet, I can get the freshest information on any subject they might cover.
I always wanted an Encyclopedia Britannica but they were always just too expensive. In the last 20 years I have acquired several complete sets which were either dirt cheap or given away.
They are just stacked up in a storage room but I am glad I have them anyway. Every now and then I will go to the real effort to find something in one of them.
You are correct of course. With the internet you can research about anything mostly for free.
My Foxfire books. A history of the Appalachian people. A good source for learning to live off the land.
I’ve found that keeping old history/science/psychology gives an interesting perspective on things. One notices huge philosophical changes in understanding. The common reaction is usually “Gee how backwards they all were” whereas my reaction is usually “ gee, how insensitive we’ve become”. Case in point; Richard Weaver’s Ideas Have Consequences.