I stopped being "Proud to be an American" when I started learning more than my Christian republican parents or Bible belt education system taught me.
While nothing that came before I was born was my fault, it's certainly nothing to be proud of, and nothing that has been happening since has been much better.
Sure, we haven't directly been carrying out genocide, but we sure support it! With the very arms used to carry it out, and intelligence support, and so on.
We haven't been enslaving huge swatches of people for arbitrary traits, but we sure do enslave imprisoned people which also due to socioeconomic reasons and good old fashioned racism also happen to be a large percentage of people with aforementioned arbitrary trait.
We may not have been openly declaring war on everyone, but we sure do like to interfere with special military operations and sabotage. Yesterday's supported insurgencies are tomorrow's enemies who have every reason to hate us.
Saying you're "Proud to be an American" today is a flashing neon sign that says "I'm a racist piece of shit who hates everyone who isn't exactly like me"
Exposing your junk to a bush in the back corner of a lot used by a school district for storage will get you on a sex offender registry, so I fully expect these Fuckwads to be slapped with sex offender charges, put on the registry, and branded as child molesters for the rest of their lives.