The way you have written this sounds both judgemental and ignorant. I am speaking to the practical reality that the entire world does not function at a single economic level. Your fairy tale dream of a world in which there is no difference from the plains of africa to the penthouses of Manhattan is foolish.

An international currency would be AVAILABLE the world over, USED the world over. But for your fantasy to be a reality we would have to consolidate the worlds population to a single continent and divide the resources evenly there. The variables from location to location, from resources to environment to government prohibit this dream from being anything but a dystopian nightmare.

In the future, you might want to try not to sound like a complete judgemental twat when responding to others. You may find them more receptive to your words if you do not begin with insults and derision.

Enjoy your bliss!