supply/demand, i.e, it was the last semi-cheap CPU for a given chipset series, etc...
Lots of things make no sense on pricing/performance...
2080Ti pricing, 7700K pricing, 4790K pricing, etc...add yours to the list. (Somewhere, someone is paying exorbitant used 6950X prices because that's the top CPU his /her mainboard supports, disregarding that a 10900X or 10900K is faster, and $500 less expensive...even after a new mainboard.)