First of all, base on my observation not all country are not yet  announced that the bitcoin is illegal. there are some country that are not prioritize or make as a big deal to the said digital money which is bitcoin in other words government did not care about bitcoin because they confidently that there is no nothing worried about bitcoin, some official government knew that bitcoin could give a problem if they give a care about to.

But generally, i think  the main reason why most of the country did not legalized bitcoin because there are some netizens that used bitcoin in not appropriate way or they used a transaction that is unusual in the world of cryptocurrency.