Yeah, that's the part I don't get about that theory, that the banks crashed the price of bitcoin. I don't see any reason for them to do that, nor do I think there's an easy way for them to manipulate the market that drastically without putting their own money at high risk.
We all know that banks invest the money that comes into their system, what we need to know is where do they invest? I don't think the majority of banks don't like crypto.
So no, in this case I don't think the correlation is indicative of causation. My guess as to why bitcoin fell a couple thousand dollars is that traders who made a profit from the price rise cashed out en mass. I mean, come on. We've seen these kinds of price movements many times before, and usually there's no obvious cause.
I think whales are starting to cash out as well, probably they would need it for something or preparation. Maybe there's something behind the works that we might not know about until it happens. It's not new and these DeFi projects are a new hype IMO and it's going down now.
Also, I could swear Pornhub already accepted bitcoin. Maybe it was some other porn service--my memory of such things isn't all that sharp since I detest pornography.
I think they are accepting an altcoin and not BTC directly. I'm not sure though. Found this article from 2018
https://www.coindesk.com/pornhub-adds-crypto-payment-option-verge-token