One downside of getting US citizenship is that if you later move to another country (your original country or a third country), you will obligated to continue to file US income tax returns, and potentially pay US income taxes. Depending on your circumstances, your tax filing might be trivial or it might be complicated, and you may or may not actually owe taxes to the US. So this might be a minor annual hassle, or it might be a painful, time consuming and expensive process. It is possible to later give up your US citizenship, but it takes time and costs money.