If something is not illegal, as in added to the code of law, it is legal. For bitcoin to become illegal there would have to be established laws against it. If there are no such laws, it's completely legal, and since law doesn't work backwards, if it's ever outlawed, nobody will be able to prosecute you for using it in the past.
Also, it's worth mentioning that some countries already have laws that make bitcoin legal and protected by law, which means if somebody steals your coins you can go to the police, like you would have if they stole physical items.
there is no law anywhere that says bitcoin violates the law, because basically bitcoin is only money that has no form, how it can violate the law, what happens is that bitcoin abusers buy something that is in violation of the law, so it all depends on its use, not bitcoin the problem, but the user has a problem.
You can say that but in my opinion every country lives in a rule, there is nothing that is not regulated in state law, and if something foreign comes like bitcoin, then there are no rules regarding that? so that the response and legal clarity is needed, as long as there are no regulations, then you are free to use it