The value of Bitcoin affects the interests of the government. Users who use Bitcoin for illegal purposes will be banned from the operation and are responsible for the country.
I think that makes the country afraid, so it doesn't use Cryptocurrency, because they feel that if citizens use Crypto, the state or the government will not be able to control it.
The main reason for a country that does not accept Bitcoin and Cryptocurrency is, because Cryptocurrency is decentralized, or cannot be controlled, cannot be regulated by a country.
This is because cryptocurrencies are decentralized and no Central Bank or government has any control over it.Only the users have the knowledge about the cryptocurrencies.Cryptocurrencies are also very volatile and unstable and their price depend upon the forces of demand and supply.They also have a risk of getting hacked.They require internet connection which is not possible in every corner of the world.They also require some basic knowledge and are very complex in use.