My phrasing was not quite correct.  I didn't mean all Americans take their citizenship for granted, but rather that too many do so.  I would say most don't, but I do think attending a naturalization ceremony is a good experience for any American just to be reminded of how lucky we are.  For me that understanding came from traveling overseas at a young age in impoverished and politically unstable nations.  It helped me fully grasp my incredible good fortune of being born here.  But as you say, there are many ways that people come to appreciate their citizenship, and many forms of service to this country.

Sorry for the misunderstanding.