Celebrity owners would have got a brief sparkle from it. Perhaps also some of Apple's marketing budget too. And they continue to own a legacy item which will have notoriety beyond mere function.
Collectors of rare historical firearms presumably don't actually fire them.
As a buyer, you would need to decide for yourself whether you want a guaranteed working firearm or not.
And in many cases, the owner will test fire the firearm before putting it on auction anyway.
Old Martini Henri rifles, dueling pistols, even muskets in some cases.