Most countries make policies to control Crypto currency
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Such Countries are: British...
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United States of America (U.S.A)
It's not actually that nations that want to control Bitcoin, such as the USA and UK don't understand it. At first they didn't understand it and some even until recently. It's just that they have realized that it is something that is ultimately beyond their control, so they have taken whatever steps they can to have some control, because they can't have absolute control, which is what they would like.
The country that has legalized it as currency, El Salvador, and those that are said lately that could legalize it, such as Honduras and Malaysia, are poorer countries that can obtain more advantages in exchange for considering Bitcoin as legal currency.
In the case of El Salvador:
" El Salvador president Nayib Bukele says the country will save $400 million a year in remittance fees by adopting bitcoin."
If Bukele says this, we may think that he is exaggerating and maybe 300 or 200 million will be saved, but it is an advantage for them. They will also profit from foreign investment, and the countries that follow them will surely profit as well.
State adoption of Bitcoin has started in poor countries, and for richer countries to capitulate, there is still a long way to go, but I believe they will eventually do so,