m0llusk gave a great answer, but to add to it, they aren't the same types of knives either.

You can buy a Victorinox Swiss Army knife (SAK) in exactly one blade steel and it's a stainless steel that's extremely soft, relatively speaking. That's actually a good thing for most casual users since it's fast and easy to sharpen, resilient to abuse, and being stainless, easy to maintain. However, it will not stand up to a lot of normal usage before the edge dulls and it just doesn't perform well anymore.

By contrast, the Manix's base model uses S30V and you'll probably get three or four times as much use from it before it dulls. Spyderco is also a "knife enthusiast's knife company" and they make a lot of their knives available in other varieties of steel too. One variant is Maxamet (a tool steel uses to cut other metals) and you'd easily have an edge on that variant last probably 10 times longer than a Swiss Army knife, but at the cost of having a more brittle edge that is much more difficult to sharpen and it's not a truly stainless steel either, so you have to be mindful of rust and exposure. If you're in a job position where you use it a lot, like in a warehouse where you cut pallet straps and break down boxes constantly, the steel variant choice can easily be the difference between needing to touch up the edge every single day vs. once a week. Spyderco also makes an entire lineup of knives that can withstand saltwater exposure without needing constant maintenance, something that would render a Swiss Army knife useless quickly. Those attributes mean the cost difference can be just about anything if the real world choice is between "useless hunk of rust" and "usable".

There are also economies of scale. Victorinox sells a lot more SAKs than Spyderco sells Manixes, they stamp out their blades by the thousands, if not millions. Spyderco probably doesn't make more than 100k Manix knives a year. A single Manix also has about as much steel in it as 2 or 3 SAKs (the blade is two or three times thicker at the spine), the handle material is nicer and more expensive, the construction is maintainable, the lock is stronger and more intricate. Also there's a machining cost difference, you don't stamp out thick blade blanks of high end steels, you have to cut them out of a billet. Grinder belts are a consumable that are used to sharpen a knife and they last a lot longer for soft steels vs. hard steels. That cost as well as the additional time an employee spends on it goes into the knife's cost. Spyderco's Manix is made in Golden Colorado, which also has a high cost of living and afaik they compensate their employees with a livable wage (I've been to their factory outlet several years in a row and keep seeing the same faces).

All that said, knives can also be pocket jewelry and there's a whole world of stupidly expensive knives out there that enthusiasts push up the prices of, just like there's stupidly expensive cars, watches, keyboards, shaving razors, dress shoes, sneakers, streetwear, raw denim, etc, etc. You can easily reframe your question as to why a pair of Japanese raw denim jeans costs way more than twice as much as a pair of Wranglers at WalMart, given that they're just pants. Or why a Lamborgini costs more than a Civic, given that they're just cars, or why a Keycult keyboard resales second hand for $4k when you can buy a Dell OEM keyboard for $15.