Second, JP Morgan is a big commercial bank but it is not the only bank globally. It does not have super powerful power to do anything that can
Third, and most importantly, the government cannot shut down Bitcoin. Neither can JPMorgan. Neither can all of these extremely powerful banks all over the world. Neither can the combined powers of both the governments and the banks. Having said this, Jamie Dimon should either shut up because they're all helpless and powerless in the face of Bitcoin or hop on the bandwagon, be cool, make money, be more powerful, and be free.
Clearly he is expressing his personal opinion which he is entitled to, he has probably seen the potentials of Bitcoin in the future and is feeling somehow threatened that a decentralized digital currency might take over as a dominant force against fiat currencies in the future. Despite his stance on Bitcoin, the adoption keeps increasing, so Bitcoin holders don't need to worry about his remarks, because it remains a decentralized asset that keeps increasing in value and there's nothing he and other haters can do about it. Just like in the banking industry you'd expect that there'd be scammers and illegal transactions in crypto, that does not mean that there are no genuine holders of cryptocurrency, it's just so miopic.