I've always suspected that my desire to own as many books as possible wasn't unique and have been curious to compare others collections.
I know quite a few people here in the UK who's collection dwarfs mine as they are in to EVERTHING including antiquarian books which I can't afford but at 474, I think my collection is ok for a man of modest means.
Accumulated over some 40 years, of the 474, 310 are bird books, this includes site guides. I have numerous other books covering Mammals, reptiles, insects, dragonflies, butterflies and moths, even a couple about sea shells. The only thing I can't get excited about is plants...
I often fantasize about winning the lottery and how I'd go on a huge spending spree and have a proper 'library' and this leads to a thing that occupied me for a short while. When does a book collection become a 'library'? The answer is, it doesn't, a library is the room the books are kept in so unless you have such you merely have a collection of books!
I've got mine catalogued for insurance and replacement would run to about £25K, that's a few birding trips and I was shocked when I totalled it up!!!
Still plenty of room as I've just reconstructed my shelves.
Andy