I guarantee you that Dimon does understand both fiat and cryptos quite well. He is not stupid but evil. He wants to retain the crown of being one of the rulers of the money system and sees Bitcoin and other decentralized cryptos as a serious threat.
He says he likes block-chain technology but does not want to loose control over the "money system". He is building a case by saying look block-chain is good but Bitcoin is bad. After that, he will introduce something based on block-chain minus the decentralization. A private institutional block-chain is clearly his agenda.
Till then, he will fight tooth and nail to create a FUD campaign with his "institutional coteries" around the world, from pseudo-democracies of US/EU to commie dictatorship in China.
But this is the exact reason, people should be more confident about Bitcoin. The threat that Bitcoin poses to these coterie shows that it is really working.