I don't think that Bitcoin will ever be able to be the global currency in the future. Instead, we will see governments developing their own digital currencies and using them. As they are not going to be volatile, it will be for the benefit of countries also. Most governments don't lean towards making Bitcoin their legal tender because of its high volatility. Bitcoin can be as much valuable as it wants. It won't help about this.
It seems that it is difficult to see Bitcoin can be legalized as a means of payment in every country,
as you said that the high fluctuations that make the government in every country have not legalized,
After all, we won't know what the future development will be, so it's better to just monitor the progress