Thanks John. I agree that between Canada and the US the hash power is more than 50% but keep in mind this is a static view of the situation.

Any attack will result in those miners leaving for Mexico, Russia or Zimbabwe. They won't remain in an unfriendly jurisdiction. In the meantime, the difficulty adjustment will come into play making other miners join the network.

When governments try to forbid something, they end up promoting it. This is why Bitcoin will never become illegal. Besides, it is already to big t fail.

Also the government will benefit enormously from the tax collected so they won't have an incentive to kill it even if they could.

Alcohol and tobacco are still legal because the tax revenue collected on those. Once something is taxed is here forever.