US Expatriates Do Not Give Up Their Citizenship
I had a reader write in the other day wanting to know information on getting a residency visa. "But I don't want to give up my US citizenship," he wrote. Moving to another country will not cause you to lose your citizenship. In fact, the government can't take it away from you under any circumstance. The only way you can actually lose your citizenship is to renounce it abroad in front of a US Consul and sign a sworn statement attesting to that fact. Even then, they won't let you give up your citizenship unless you have already acquired citizenship in a foreign country.
Acquiring foreign citizenship does not mean you lose your US Citizenship, though. The Supreme Court has ruled that US recognizes dual citizens. Even if you acquire citizenship in a foreign country, you still cannot lose your US Citizenship. Even if the foreign country you acquire citizenship in requires you to renounce your previous citizenship, it still won't have any effect on your US Citizenship. They can make you swear to whatever they want, the only way you can lose your US Citizenship is by going before a US Consul and doing so.
So, if you are thinking of expatriating but worried about losing your citizenship, you have nothing to fear. Explore the world outside your country, meet new people, have new experiences. You can always come home if you don't find what you're looking for.