It can exist, but for how long? If my government tells me that I will go to jail if I use it, then I would probably stop using it, and even if ever do, it would be for transactions and very quick, but most likely I would not. Which would hurt me a lot believe me, I get paid in crypto, so if I suddenly stopped getting paid, I have no salary and my whole life would be ruined, but I still would stop. I rather go work a fast food joint making minimum wage then have the possibility of jail over my head. So it "can" be used, but would it? I am sure there are plenty of people like me who would stop using it.