The way I understand money is to treat it as a technology. A technology is designed and operated to serve a purpose. The money of countries like the US and Europe is intended to serve as a medium of exchange, a temporary store of value, and a tool of government tax and monetary policy. I think it's expected that people will hold onto a minimum amount of money, and store the bulk of their wealth somewhere else. Most people don't have substantial wealth in the first place.
Bitcoin is intended to serve another purpose: To demonstrate the behavior of a money system that is not controlled by a government.
As with any technology, people use money if it's useful to them. If a country has a poorly managed money system, then people start to use the money of some other country, or barter. If bitcoin has a chance of supplanting government money, it will happen when bitcoin works better for the people using it. I suppose this could happen sooner in countries that have really bad money, or if the use of government money becomes prohibitive because of transaction fees.
Bitcoin is intended to serve another purpose: To demonstrate the behavior of a money system that is not controlled by a government.
As with any technology, people use money if it's useful to them. If a country has a poorly managed money system, then people start to use the money of some other country, or barter. If bitcoin has a chance of supplanting government money, it will happen when bitcoin works better for the people using it. I suppose this could happen sooner in countries that have really bad money, or if the use of government money becomes prohibitive because of transaction fees.