In practice, you can only ban yourself from using Bitcoin.

Why is @Lyn Alden worried about the government banning Bitcoin then. She doesn't know how it works.

Who said that? It can be banned, but the ban is costly to enforce and thus just drives it into the black market. And so any bitcoin user would much prefer to live in a jurisdiction that is not authoritarian enough to ban the use of a decentralized spreadsheet.

Your Bitcoin friends say that. Representative example: