system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can't we have one currency for the whole world?

i get that it might be difficult at first and the change may take a while but would it be possible?
gpt
Who decides how much of that currency is printed?

Some countries have rampant, terrible inflation.  If they share the same currency as their neighbors, both they and their neighbors have to keep up with the inflation.  If they have a *separate* currency from their neighbors; their inflation effects only themselves (and people that rely on them strongly).