There is more than 7 billions humans and 200 countries in earth. There is wars, we are not united. This is why there is different fiat currencies.

There is technological disparencies, 40% of the world population have an internet connection (in third-world countries, this mean going to a cyber cafe), even less have a smartphone, even less have a smartphone with internet connection.
In many places even the ATMs regularly get out of service because of shitty internet connection. God, even the connections of cyber cafes drop daily, sometimes for many hours.
In still many places, a lot of small family businesses doesn't even have a land-line phone.
Cryptocurrencies are not an option in these conditions.

It's not about "would it make sense or not".
It is simply something that won't realize.

It would make sense that all the people around the world start using the same language. Do you think we will?

😘😘😘