I'm almost 24 years old, born and raised in the United States of America, and lived there for nearly the first 24 years of my life. Patriotism was a value that was instilled within me from a very young age.
My father's side of the family was very military and my mother had military veterans in her family as well. As such, it was a huge part of my upbringing, and when I decided not to go into military service (or on a mission, for that matter) I was really bucking my family's system.
I'd say I was about a junior in high school was when I started really losing my identity as a patriotic American. As I was exposed to the realities of the country around me, I became aware of so many of the inequalities that plagued the United States that are less of a problem elsewhere: everywhere from LGBTs not being treated fairly or being afforded equal rights (most democracies around the world afford LGBTs full marriage rights), to the complete ignorance of medical ethics in the respect of genital integrity of baby boys (routine infant male circumcision is only performed for non-religious reasons in the US, and 80% of men worldwide are intact, and that's not even going into the reasons why it shouldn't be done), and even to the non-Christians who are heavily persecuted in the US (it's not just atheists, it's all non-Christians, they are treated like second class citizens).
Capitalistic greed, selfishness, imperialism, mistreatment of minorities, among other things all led to me losing my identity as an American patriot and the more I found out about how bad things really are in those terms, as well as learning about all the government scandals that have gone on and are still going on in the US, I eventually grew to really hate my home country, so much as to start turning my back to the flag during the playing of the 'Banner to public displays of flag desecration.
I only grew to become even more anti-America during my short one-year stay in graduate school (where I worked as a teaching assistant and also had plans of becoming a professor of mathematics), and experiencing first hand the lack of motivation and discipline in students today.
Teaching mathematics to a bunch of lazy, unteachable, idiotic, party-animal undergraduates with no work ethic or academic integrity was physically and emotionally draining. Why do you think I wound up failing two-thirds of my students in all three classes I taught during the time? However, I know the reason they are the way they are is the US education system is weak, and they don't get their butts kicked hard enough in primary and secondary to have any sort of work ethic at all. Graduating high school is, to quote a Geico commercial, "so easy a caveman could do it."
So here I am now, in a foreign country, and a renounced US citizen. I totally understand that by doing so that I now have no protection in any country, because I am now a stateless person (contrary to popular belief citizenship in a foreign state is NOT required for renunciation of US citizenship). To be able to call myself an "ex-American," to no longer be subjected to the oppressive, discriminatory, greedy system that plagues America today, and to no longer be viewed as a second-class citizen for being a bisexual atheist, is a great feeling.
In short, I've never felt so free as I did on the day I renounced my US citizenship.