Would a universal currency work?

What if I told you there is going to be a universal currency called the Doan one day? Chances are you wouldnt believe me and rightfully so because no one would ever agree to a universal currency. Why wouldn't countries agre on a universal currency? The reason why I believe countries would not all agree to a universal currency is because with it there would be less competition between countries. Less competition is not the only bad factor in a universal currency but implementing one would be near impossible. If there was a universal currency poorer countries would be in danger because people would simply not be able to afford anything. Another factor is that a lone country could screw up the value of the Doan, which would cause a ripple effect to everyone in the world because everyone has the same currency. A universal currency most likely will never work, but our currency system now is not working either. Putting the faith of the value of currency in the hands of the people was never a smart idea which can be seen from contagion. People tend to panic when it comes to money and they act on impulse rather than reason. There should have been no reason for Thailand to affect all of those other countries but the reason why it did was because people panicked and quickly lost faith. There are many other issues with the system we have now such as how banking works and how easy it is for countries to conceal how much money they really have. I believe the current system we have is here to stay.