Bitcoin has never been worth $0 not even when it was being traded by just a few thousand people around the world back in the early days. Even without Bitcoin being listed on an exchange it at least had some form monetary value.

We're at a point where if countries ban Bitcoin, it will more than ever stimulate peer to peer transactions, and governments are aware of that. Instead of being stupid enough to ban it, they'll try to find a mid-way 'solution' which is to regulate the market.

The fact that you don't seem to understand that shows you little you know about Bitcoin or the state of the whole movement/ecosystem.