Your fear will only come true if massive inflation hits most countries and only a few nations try to control the world. Then we might start using Bitcoin for transactions as a way to fight inflation. But that's not why most people buy Bitcoin. Most long-term holders believe Bitcoin will bring them profit, and they still trust fiat money for everyday transactions. Even if there are signs that inflation might rise soon, for now, the inflation rate is still tolerable in most big countries, so it doesn't really scare ordinary people.