Let's face the truth, it is only in theory that cryptocurrency is a threat to banks/financial system. In reality, the banking/financial system is so big that crypto's threat is not significant at all. Majority of cryptocurrency investors are not really interested in crypto replacing the traditional financial system, they are just interested in it creating enough hype for more people to get in so their investment can skyrocket.
Think of it, if crypto was really a huge threat, don't you think we would have enough regulation by now?? what is you opinion??
The financial system and cryptocurrency are tools for people to transact and move their funds, it's not against each other, both coexist to provide more alternatives for us.
There are several advantages and disadvantages for both systems, hence both should be used to collaborate in order to complement each other's deficiencies.
Although not all countries issue comprehensive regulations regarding the use of cryptocurrencies, several governments have issued rules regarding cryptocurrency transactions, although most govern transactions on exchanges, kyc, money laundering, and taxes.