IF the whole world ban BTC at first BTC will Crash very hard but only for a few month, Demand will be increased while there will be no Legal Seller, All trade will go to undergrand and Black market and illegal traffic, sellers will start to selling BTC 50 X more than current price. BTC will be more expensive, As simple as that,
That was an answer for these who said BTC will die if whole world Ban it, So no BTC never Die.
Why would the demand increase when it is illegal?
BTC is still being used in illegal ways in blackmarket and other stuff,
But it still doesn't skyrocket just like you mention.
If the whole world bans it then it would surely fall but it wouldn't completely die.
Other crypto would take over for sure.