This is a very interesting question. The sovereign nations issue their own currencies and are taken for granted by many people, but few consider whether this is the economically optimal option.
Well rhe world where we aee living will be better if we have single currency since our major problems will be non existent just like the poverty we are facing nowadays rhe third world country labels, and our children in different places in the world will habe a proper education and enough supplies of food which they lack nowadays, cause the price of the goods were a lot cheaper than what it is today.