The government should not be stopping there citizens to accumulate and hold Bitcoin because is not a criminal act or something that will destroy a country so I don't see any reason why some government will not allow there citizens to engage in Bitcoin fully.
I don't know why Bitcoin is illegal in other countries but Bitcoin is illegal in our country for various reasons. The government of our country thinks that if Bitcoin is legalized, it will be easy to launder money through Bitcoin in the country, this is the main reason. Besides, they think it will be easier to buy illegal weapons and various illegal things using Bitcoin. Now the government of our country only thinks negatively, they should also consider the positive aspects. Now the popularity of Bitcoin is increasing day by day and Bitcoin has been legalized in many countries. Big companies in the world have invested in Bitcoin. So the countries that are currently against Bitcoin, hopefully those countries will legalize Bitcoin in the future.