Does owning an XCR give you some kind of psychic insight into why a different owner might be selling theirs or something?
The OP asked why so many people are selling their XCRs. You don't have to be an XCR owner to speculate, and since there is no actual data available, all anyone can do on this subject is exactly that: speculate.
There have been several theories advanced here that make sense to me...tax time, lot of money to have tied up in a gun if you're not using it, non-restricted novelty might be wearing off for some, replacement parts have traditionally been hard to get from Robarm, small company with a history of abandoning platforms might make some people nervous, some people might be turned off by the company's CS approach, might just be a coincidence...who knows? All valid reasons to sell a gun, just like "don't want it anymore".
None of this should cause anybody to freak out. Mentioning reasons why someone might want to sell something, in a thread called "why are so many people selling this thing" is not bashing, it's offering an answer to the question that was asked.