As far as I think the countries that do not allow the use of crypto may be they have not controlled this market. Controlling the investment of citizens will benefit the nation.
It is not possible for any government to control bitcoin and that can be the main reason that still they are not allowing and making bitcoin as lgal currency in their country. But it is for sure that in future all such countries will make bitcoin a legal currency. Because bitcoin is the need of the modern time and the young generation feel it more easy to use bitcoin instead of fiat currency. Therefore i think that they will very soon change their decision about bitcoin and will make bitcoin a legal currency in their country.
If the generation of the people like 40 yrs old and below will become the dominant generation then the cryptocurrencies will be used because the people who are older than 40 yrs old are not that open minded when it comes to the new technologies or inventions. Fiat money is still good but if we will go for cryptocurrencies then we will have a better flow of economy.