At least our addiction is that of a useful object. I don't think in any one day, you can go through life without using a knife at least in the kitchen. If your working the trades, you need a knife daily. Even in an office environment, there's boxes to open, mail to open. Let me see the non knife people make dinner with no knife.
People collect and get obsessive over a wide range of objects. Look at stamp collecting. Some stamp nut will go ape over a little half inch square of fragile paper that has no real use in the world. It can't open a UPS box that has been taped shut, or slice up that steak just off the grill, let alone help make a campfire or cut a piece of rope. Same for coin collecting, beer can collecting, or any other collecting.
We happen to obsess over man's second oldest tool. Sharp objects have stabbed, cut, and sliced it's way into human history by allowing us to evolve and process meat for the protein that let our brains grow, from Java man to Neanderthal to Crow magnon man. From a piece of sharp stone to finely flaked flint, to bronze, to iron, the knife evolved right alongside us every step of the way. Wars fought, empires built, new lands explored, with the knife on our side. From some Roman legionnaire honing his gladius, to a mountain man honing his Green river knife, the blade has been, and always will be mans companion tool.
Only in the most recent times has it fell a bit out of favor. I know I'm an old fart now, but when I was growing up, if a man had pants on, there was a pocket knife in those pants somewhere. It was even expected. Many women also carried a small pocket knife in a purse. Every five and dime store had the stand up cardboard display right up by the cash register with the small one and two blade jacks for all of .99 cents, in case you needed another pocket knife it was there as you checked out.
Our modern society has demonized the knife to a strong degree, but it is still a useful, and sometimes a needed object. It is my opinion that every man should have a sharp edge on him. My old man used say, you can never know what you will have to deal with when you leave your front door. Twice in my life Ihad to use a knife in an emergency. Once a life was at stake, when I had to crawl into an upside down wrecked Datsun/Nissan little car that had rolled a few times. I used the sheep foot blade of my Buck stockman to cut the seat belt that was refusing to release, and I don't think I could have done that with a special coin, stamp, beenie baby, beer can, ashtray, or any other collectable thing. But man's second oldest tool let me get the lady out of that burning car.
Yes, we obsess over the knife, but if push comes to shove, at least it's a useful object in the real world where nothing is certain. We all may not agree an what is a good knife, just as car obsessed people can't agree on Ford VS Chevy, or the bike nuts can't agree on Honda vs Suzuki, or Jim beam vs Jack Daniels. We can't help it, we're all individuals, like snow flakes, all different. And with differing opinions. But at least we all keep a sharp blade or two on us, so we are bit more functional in the real world if things go south.
I can think of a lot worse things to be obsessed over. Knives are legal, cheaper than drug, can be carried around in a pocket, and can save a life. Obsess away!