Keep in mind that the US purchased EURO bonds(?) at the height of the EURO crises, so America had a vested interest in the success of the EURO. Returning to the individual national currencies would have been a fatal mistake given the delicate nature of the global economy and possible multiple defaults from Greece, Italy, Spain, Ireland, and France.
For China, a country whose "bragging rights" focused on how much money they SAVED when buying CHRISTMAS gifts, the EU, EURO, and the US economy thank you for keeping the EURO afloat.