I do buy physical books (mostly comics, books on Graphic Design, art books and non-fiction), but more and more, I'm looking for ebook versions as well as/instead of. This is primarily for two reasons: 1. Space, and 2. I love the idea of having my library with me at all times. I love print, though, and especially the things you can do with it like die-cut, varnishes etc., so I'll never stop buying them, I'll just be a bit pickier in future.
I keep my books as long as I can, but I do have to cull them from time to time. There are certain books I'll never be able to get rid of, and those I keep in my study/office (for sentimental reasons, value etc). Others like novels, I tend to only read from libraries and never buy.