The US Supreme Court has taken the view that citizenship is a basic Constitutional right, so it's almost impossible for a natural-born citizen to involuntarily lose citizenship. Even in the cases of acts against the United States, in some ways its easier to prosecute a citizen than a non-citizen.

On the other hand, I've heard people complain that the US makes it difficult to renounce citizenship, even if you really want to. Don't plan on this as a way of escaping your back taxes.