I think it is only illegal if there is a law that makes unregulated market illegal. The crypto market in my country is still largely unregulated but the people are free to use and trade any cryptocurrency from both local and international exchanges. Some countries have already imposed their own regulation to curbe some illegal activities and protect their people financially.
Exactly. Without law stating prohibition of using it makes it still allowable or legal. Just like generally speaking, theres a lot of bad activities being performed everyday but as long as there is no law stating it is prohibited and punishable it remains legal. Here in my present location it is illegal but foreigners can open bank accounts.