>What it would make a difference with is crime. All the drug dealing, child prostitution and money laundering from those businesses would be fucked overnight. Sure they can still do it, but it's a hell of a lot harder when everything is recorded.
"Criminals will stop using cash immediately when we make it illegal" - it doesn't work like that. Criminals would just adopt another method of payment. Even China, the country with the most authoritarian, all-pervasive internet firewall, hasn't managed to stop people using crypto to pay for sex and drugs online. There's pretty much zero chance of the west tightly controlling the internet anywhere near as much as China any time soon, so there's basically no way it could effectively ban crypto either. Even if it did manage to completely ban crypto, however, it still could not stop criminals just resorting to traditional forms of cash, backed by gold/silver/gems/precious metals. Or do you think every country in the world is going to ban all their citizens from owning any precious metals?