The U.S. dollar is the world’s reserve currency, so generally speaking, if you are not planning to travel to foreign countries or do not have the need for foreign currencies in your business, you might as well stay with U.S. dollars.
If you are using foreign currencies in your investment portfolio, you must be prepared for volatility and continue to educate yourself on the Forex market as well as international trade. The famous example of George Soros, who almost destroyed the Bank of England, and made a couple of billion dollars along the way, might not necessarily be applicable to you.
If you tread lightly and are prepared to lose anything that you invest in Forex, you can eventually learn how to make money on positions in foreign currency.