It's not all that hard to understand, even from a "to each his own" view point. And actually it isn't a requirement that you understand it, only that they do. Now if they are doing it from compulsion, and can't explain it, then they may have a problem. I think I just bio'd myself. lol
Some such as yourself, view knives as tools meant to be used. Fair enough and perfectly valid.
Others view knives as an investment. Not a very good one IMO, since there are far better places and ways to grow your money. But if that is their thing, so be it.
Still others view their knives as art. This can take on several forms, starting with the pricey, highly ornate, engraved, embossed, embarrassingly over the top examples some have made and purchased. But others view knives as art from a different point of view. Sleek lines, immaculate fit and finish, brilliance of design or concept, engineering, anything can rise to the level of art in the eyes of the beholder. (or is that beer holder?) Just as few would use Da Vinci's "Mona Lisa" to cover a hold in the wall of some tenement flat, some knife knuts refuse to use their collection of art pieces to cut so much as a breeze.
I personally have my feet planted squarely in the ground for both, users and art. Some I buy just for the beauty they display in one form or another. Others I buy strictly to be my EDC, or gentleman's knife, or user come hunting season. Some I have bought and not used or carried, or sharpened. At first because they were only to be collection pieces. However, I am finding that with some of them, they no longer hold the allure for me that they once did. Call it growth as a knife knut, a return to sanity, or ramping up to higher end knives, now believing, hey it's only $400!. lol By keeping them in pristine unused condition, I know I will get the most I can for that knife if I decide to sell it later on. So on that end, not using the knife, lowers my out of pocket expenses should I no longer feel the need to hold onto it.
So go ahead, I completely understand you thinking of knives as tools and would never own a safe queen. Perfectly sound argument. Though it does not apply to all knives very well. It falls on it's face when talking about museum pieces. Anyone using King Tut's golden or meteorite daggers to cut anything should be drawn and quartered.