The way I understand is like this. Developing Bcash must've cost a fortune, so now is the time to get it all back by selling to the next sucker. Jump of $500 in a couple of dollars. Only a fool will not understand.
I'd like to believe so, but Bitmain, Roger Ver and others have staked their reputations on this. I don't think it's just an overnight cash grab. I don't know how sustainable their manipulation really is, but I also don't think the kind of time and money they have invested (mining and marketing BCH) was intended to climax with one night of price pumping.
The spam attack on the BTC blockchain has been impressive, too -- I've never seen anything like it. And Bitmain is only accepting BCH for payment for mining hardware now. It's an attack from all directions..... I never would have thought Jihan Wu would attack Bitcoin so openly considering how deeply invested Bitmain is.