The U.S. Dollar has a preeminent role as a currency within the global1. This is because of the following factors:
- Safety: dollar is baked by the U.S. military and economy while being maintained by the Fed.
- Trade: global trade is often invoiced in dollars, even when neither party is american
- Currency bloc: Many currencies peg to the dollar.
- Lower cost: often loans are in dollars can be had for cheaper than other currencies
- Liquidity: dollar market is deep and liquid compared to other currencies. This is why even less friendly nations may hold large amounts of US treasuries