Another reason could be, for those peoples who move large amounts, maybe corporates, maybe terrorists or maybe money launderers those who need more & more privacy... not sure tho.
There is LocalCryptos to avoid KYC but I guess volume could be an issue.
if you do able to find some buyers of said sellers. They've done it thru p2p transaction and of course that would be on lower than on market price
and usually these kind of transactions are for bulk ones.
To my understanding, those who want major volumes at rates under the market go established OTC -- trusted custodials with a reputation and even insurance. I can't see them coming here to look for a lot of unknown variables and discuss such transactions in a public space.
Much less so if KYC's a concern for them. They'd definitely just seek out an offshore OTC via a trustee. OR just go Bisq and the like, P2P with escrow and no KYC. Volume is an issue solvable very quickly if price is below market.