Do you think if BTC had a stable price which could only be altered by $0.01-0.10 it would still be as popular and as used?
If bitcoin is stable then more people will adapting bitcoin for business, more local shop will accepting bitcoin because they can calculate their profit, if bitcoin price is unstable then it will be good for trading, so no matter what is happening - bitcoin will be popular anyway
Probably, in that case, it would be not prohibited by many countries, and most of the people would use it as the currency that is very convenient for online operations.