I remember watching tv late at night with my wife years ago and flipping through the channels to pause on some home shopping show that featured "rare" beanie babies for hundreds of dollars. We stared in amazement as the counter on the screen showed the rubes getting fleeced before our eyes as a Jim Skelton-style huckster breathlessly extolled the rare and incredible opportunity to own a small stuffed animal for $249 or whatever. A couple of months later the craze ended and a lot of people were left holding value-less stuffed animals they'd paid hundreds for.
Of course, that's silly, it could never happen with knives, right? Let's not forget all the people who paid $1000+ for a Hinder flipper (that doesn't really flip) a few years ago. Those knives are going for rock-bottom prices now, as supply caught up with, and then exceeded, demand.
If you try to game it, you'll have to aim for being early rather than late. Let's say Mick "I'm a proven dishonorable douche" Strider's company stopped making pie-slice handled finger choils (with bonus tiny blade!) and you decided to buy up a bunch of SnGs or whatever while they're still going for $350 or whatever on the secondary. Sure, prices may go up, but as demand then rises what's to stop the liar, er, knife-maker/ex-mercenary/lol from cranking them out by the hundreds again to tap that new demand, thus deflating the market? Nothing, in fact it's entirely likely, that's how market forces work.
Invest in the market, don't invest in knives.