Honestly, they are just another book. This may sound stupid in someone else's mind but books can be easily replaced, lost or borrowed unless they are precious in a way that it is irreplaceable. First editions are considered priceless especially if it's signed but for me since I don't own anything signed yet, I don't know the exact feeling of owning a book that is irreplaceable.
If you are a serious collector then first editions are your gems, but for me who buys books in bulk and cheap (some books are an exemptions though) they are just another book. Well maybe in the future I'll change my mind, but as of now that's where I stand. I do admire those collectors with massive book selections.