[solotronics]

Enforcing illegal torrents failed. I think a cryptocurrency ban would be similar. Also, the US made it illegal to hold gold between 1933 and 1974 but almost nobody turned in gold to the feds. https://en.m.wikipedia.org/wiki/Executive_Order_6102

[cortesoft]

They enforce it when you buy something real with the coins. A torrent is the thing you want, it isn't a currency to buy the thing you want.

[Erlich_Bachman]

Both are essentially electronic systems of information on a computing system, a format and a protocol of communication through the internet. In terms of technical difficulty to enforce them it would be very similar.