Is the drop due to the saying by Calvin Ayre that they will give up on the Bitcoin Cash, and concentrate on the Bitcoin version of the Satoshi Vision? So he will wage a war against Bitcoin instead of Bitcoin Cash? That could damage more to the bitcoin itself.
I am quite sure that most of it is being driven by Jihan Wu financing his "War on BCH-SV" coupled with Bitmain cashflow issues and having to dump a ton of their BCH (and probably other coins as well) horde.
I have never understood the whole "BCH" junkcoin push by Wu - it's not like cryptocoin NEEDED yet another junkcoin, and the only reason BCH ever got any traction at all was Bitmain FORCING it to be used to buy their miners for quite a while.
Most likely the reason why Bitmain holds so much BCH is because they got greedy and didn't sell at $3000-4000 last year when Coinbase added it.
I am sure they sold it in small quantities but not enough. They were probably expecting $10000 BCH and were going to sell it done. Their BTC they probably sold way too early and didn't get a chance to sell at $20K.
The WU is a pretty smart individual but everyone makes bad investment decisions from time to time.