I do not understand, if just allowing crypto to be used in some trading cripples all of your economy, I think your economy should cripple anyway, you are very weak and you can't handle even a slight bit of competition.
That little competition could turn to a bigger one, once people sees the worthiness of crypto they might just jump all in on that which most of the government does not want to happen. It is understandable how every country has its own government that has a different stance on things, it shows the diversity of how every one of us think. Crypto is small, still, but the potential that lies within is huge.
Crypto is far superior to any fiat in the world but it is not superior enough to actually destroy the financial system as a whole, it is just an alternative and that is it. Until you can put your crypto into bank, have a crypto card, pay everything with crypto and just remove fiat totally out of your life without ever using it again and fiat cash becomes a novelty, I think it can't destroy financial system. And for that to happen we need at least few decades of crypto surge constantly and I feel like that is not going to be stopped this way neither.
The problem with crypto is that it separates the citizen to its government in terms of finance monitoring, government would have a hard time tracking illegal movements when we use cryptocurrencies, on the other hand most of us just wanted to have a convenient in transaction which the government clearly sees, but still the threat of using cryptocurrencies is not a joke to for them to just set aside. It cannot destroy the financial system but it can weakens the financial system, hence crypto is always on talks with the possibilities.