Some scholars have offered some insights into private cryptocurrencies and central bank digital currencies.
We do not mention CBDC, nor China. But they questioned whether bitcoin could be widely used around the world.

First, we are in the era of sovereign countries. Currency is a symbol of sovereignty. Monetary policy needs to regulate the economy, while private cryptocurrencies are decentralized and decentralized, and the government does not have the right to issue and control the currency. It is very difficult for a country to give up such a sovereignty.

Second, the conservation of the total amount of Bitcoin makes it face a dilemma. The development of the global economy and the development of trade requires more liquidity, and Bitcoin has a constant supply. If we give up constant supply and grow at a fixed growth rate, it does not meet the requirements of macroeconomic stability for currency.

Third, the marginal cost of mining Bitcoin is increasing. Because the number is constant, the beliefs of inefficiency, environmental protection, and decentralization also have a dilemma. Many studies have shown that Bitcoin is now concentrated in the hands of a few people, which is also the inevitable result of the final competition in a so-called decentralized market environment. At this time, it is said that it will be decentralized, and finally it will be concentrated in the hands of a few people, and the belief will collapse again. Prices are too volatile for money to perform its basic functions.

Therefore, it is difficult for private cryptocurrencies to become the legal tender of most countries, let alone international currencies.
Rebuttals are welcome.