It is easy to be snobby about people who fill their bookshelves in this way – but “we’ve all got lots of books on our shelves that we haven’t read,” Hubbard points out

I think I've read everything I have on my bookshelf outside of some fiction books, almost entirely by Neal Stephenson (I ordered everything he wrote based on how much I liked his early stuff, then didn't like his later stuff as much as I did his earlier), a few books that I was gifted and didn't want but also felt guilty about throwing out, and some reference works that aren't really intended to be read straight through.

I do have ebooks that I haven't read, though.

Oh, and there's a textbook on statistics that I never finished.

There are maybe three books in the queue that haven't made it to the bookshelf, one on war planning in the early 1900s, one on political economics, and maybe one or two others.

EDIT: and somewhere around the house I have my currently-in-progress book on Cold War-era submarine design, but that hasn't made it to the bookshelf either.