Because they work.
Because we the people on this knife site are very obsessed by our hobby of knives, we tend to be very blinded by the simple fact that, we don't need a 300 dollar knife to get things cut. Nor do we need a 100 dollar knife. In fact, a great deal of the rest of the world seems to get by very nicely with knives that most here would turn their noses up at. Knives like Douk-Douk's, Opinel's, Mercators, old rusty Schrade Old Timer jacks, and bargain basement level SAK's like Victorinox recruits. Somehow people from all walks of life go to work, come home and fix dinner with 3.99 kitchen knives from a big box store.
I went through my high end knives era. Once upon a time I though my little collection of Randall knives were the cat's meow. Going hunting? I was sure to have my Randall bird and trout knife on my hip. Did a great job on everything up to and including white tail. Going backpacking? My Randall 14 was up to anything I though I'd encounter in my wildest Walter Mitty day dreams.
But as time went on, and I lived long enough to gain some real world experience, I got to see the other side. Friends and co-workers who did not share my obsession about knives, seemed to get that opening day buck field dressed, or that stringer of fish cleaned, or even that piece of rope cut, with very common low budget knives. It's like being a watch nut, or car not, or any other obsessed snob. The car guy things he needs a 50K hot rod to just go to the store or beach, while the non car guy is happy his Toyota runs so well and he goes anywhere he wants. The watch guy thinks he needs thousands of dollars of Rolex on his wrist while the non watch guy is happy with his Timex Expedition.
I've long since lost my appreciation of the high end stuff, and the money from the Randall's when I sold them off let me and the better half do a month long camping trip around the county to all the big National Parks. memories that will last a lifetime, of waking up and finding a herd of elk grazing by our tent.
Now for the past 20 years I've used just the budget cutlery. Somehow I'be been camping, fishing, traveling, and gardening, with budget cutlery and they work just fine. Come on, do you really think that piece of twine you cut, or the box you opened cows the difference between a budget blade or a high end one. When you get right down to it, any decent well sharpened blade will cut. You don't really need an expensive knife. It's a want, because of our obsession as knife nuts that we spend what we do on knives. But keep in mind, we, the afflicted knife nuts, make up probably less than 1% of the general populace. The rest of the world doesn't care or even take notice what is stamped on the blade of whatever they use to make dinner with. Heck, most of the rest of the world does not even carry a knife at all. Just like the vast bulk of stuff signed these days are signed with a Bic or Papermate and not a expensive collector pen.
It's okay to like the high end stuff. Just fine. But don't get your nose too high in the air, because you're just exercising a want vs need. To the rest of the world, we the knife nuts are the weird ones. There's probably more real work being done with an Opinel or a SAK than any other three brands of high end one hand folders with a price tag higher than the regular working man makes in a week in some countries.
And then, there's the wonderful liberating feeling of carrying a knife that you can lean on, use like a better, and if it breaks, you can buy another at the next big box store, or get online for less than the price of a couple of beers at your local pub.
A little snobbery is not bad, and it's good to take pride in what you have. But never loose sight of the real world.