Frankly, I think this is the "secret" to their success.
Spyderco makes all kinds of knives that appeal to different kinds of people.
No one wants to buy ALL of them (I think RamZar posted that there were around 80+ new releases in 2018) but they tap different markets. They sell their knives to a wide array of people, just like Kershaw and CRKT do but, while Kershaw and CRKT, stick primarily to the lower end, Spyderco also hits the mid-market (where ZT is) and now also the upper end w/the Drunken, Subvert and Paysan (competing w/the likes of CRK).
This is actually a very smart multi-tiered marketing strategy that they probably paid some very high priced MBAs to come up with.
PS: I don't think that it is an intentional part of their marketing strategy but I also think that their early release teasers about upcoming products (and the delayed release dates for those products) also increases demand for those products, which almost always seem to sell out initially which of course increases demand even more for that item -- just look at the Smock and Drunken for examples of that.
They've certainly got me hooked, I've bought over 100 of their knives, both old and new, and I continue to buy more.
Well done, Sal!