It's odd, isn't it? Some kind of vestigial addiction? With me it started over 50 years ago and reached its apogee during my bachelor years, probably hitting close to about 100m of bookshelves. Homebuilding with Mrs Ham was the first Great Cull, coming down to, say, 50m. There have been a couple since then, each one gets successively harder to deal with, no matter that I may not have opened the book for upwards of 20 years.
This time around I have brought it down to probably less than 10m, and addressed stuff like the poetry collection. Elizabethan love poetry? Why would I want to look at that? Tennyson? There's a reason why I haven't opened his collected works since whenever. The "literature" category took a hammering as well. Yes, I know I enjoy Muriel Spark, but I can get them on Kindle now if I really want to (and, I have on occasion). Priestly? hasn't earned his space. etc.
The remains form an odd collection. 100% of Pratchett's lifetime output, mostly 1st editions. A few art books. A few odd 1st editions. A few decent car books (the indecent ones moved on in a prior clearout). A few kids books. A few, just because. Many of those it is hard to imagine not having, just sitting there is a reminder of other times.
I doubt I'm alone.