Banning cryptocurrency only fixes one side of the global-internet-being-security-broken problem. If you're a nation-state actor and you can still break into computer systems throughout the world, you can still: - Manipulate and profit in foreign stock markets by short/long selling based on insider information - Choose who gets elected by making dirty laundry public - See military planning by the enemy, live, as it ha…
Grandma doesn't have security audits, wouldn't know how to do one, and couldn't afford it if she did. She is the victim here. She might call the police but they will file a report and forget it. The only chance of getting caught is some larger agency like the FBI picking it up and going after you. This is highly unlikely.
The only thing stopping Grandma from getting ransomed is making it difficult to pay. If your ransom depends on walking Grandma through the 15 step process of paying you, then it's unlikely to happen or be profitable.