Gents, the truth is there is no right answer...only the answer that is right for you. And even that may be different from time to time.
I've been a moderator on the largest custom and production knife enthusiast website for over 16 years and this issue is commonly encountered.
The bottom line is that some folks will pay more for box and paperwork. Some folks don't care. Sometimes the boxes (and/or paperwork) matter, sometimes they don't.
Depending on rarity and availability, some pieces will bring considerably more in the marketplace if pristine...sometimes not.
What have I learned over the years? If I purchase a high dollar item it is mine to do with as I please. If that makes some folks blanch because I've sharpened a hard to come by custom knife, so be it. If I choose to leave one on the shelf for any of a number of reasons, it's no big deal either.
Life is short. Enjoy your guns in whichever and whatever legal way floats your boat. If you want to make money, you should probably make alternative investment decisions for the long run.
Me, I like to shoot and enjoy my guns and keep them properly maintained in case called upon for more than recreation.
Boxes and paperwork? If I have the storage free, sure. But I won't lose sleep over it unless it's required for authentication somehow.