If government "Ban" bitcoin, they can only kill the merchant markets. So you will find it difficult to buy something local.
You can still aquire bitcoins and save it in cold storage. You can go on a extended holiday, in a country that excepts
BTC and pay for your tickets in
BTC and the hotel and have some spare to buy some food.
So the
BTC is not worthless, because you can live like a king abroad.
It's the daily survival in your local country, that would become tricky, if it's banned by your government.