I recently visited the Philippines and a friend bought some knockoff Crocs at a market. The little rivet thing holding the strap to the shoe had the logo printed right on the exposed plastic, and after a few days, the logo was mostly scratched off. But my wife's Crocs that she bought a decade ago still look fine because there's some sort of sealant on top of the logo.
Is that worth an 800% markup? Probably not. But the knockoffs do cut some corners that the genuine articles don't.
I don't know enough about shoes to explain why, but the difference in comfort level was huge.
The only two modes of failure of this sandal is "drying up" after a couple years and broken thong straps (yes, 3rd parties sell those as replacements..)
I guess they make sure they have cheap offerings and are always investing in design and marketing so no one can enter this market..
You can get the genuine ones for $18 to $35 on ebay depending on the color, so while I'm sure you can save some on clones it's not worth it for the durability and comfort.