I think in this instance is a bit different, we are talking about reaction in this case to the supposed aggressor. I won't lie I am guilty of this myself at times, but this can also be detrimental on many interactions (depending if we are talking about a stranger vs a friend or family member). To be clear, we as humans are hardwired to always prioritize our well being first, and sometimes that does contradict on how our behavior is expected. However, on every instance of these events we should be able to first think how we should react and then do something about it (on a flight or fight situation this does not exist, since at that point our reflexes and reactions prioritize our well being first no matter what). Meaning, for the most part we should try to behave in a way that de escalates a situation instead of escalating. And for my understating, this is where the kindness argument comes in. If a situation can be de escalated by not responding on the same way as the aggressor, you can potentially get out of the aggression situation to a more neutral ground.

PS: regarding your internalization bit, I cannot say what is the best way to live your life, but from my personal experience, having someone to just talk to about these subjects can be extremely valuable. Just by offloading in a constructive way to someone (meaning, no lashing out) can relieve a massive burden out of you (and as for me, I do not believe in the methods where there is not feedback, e.g.: diaries, but that is my take)

I am not from the US, but I do see in many places (if not all) this "us vs them" mentality. From what I know, specifically in politics, by giving a "face" to a specific problem and then lash out on that "face" to have more influence has been a constant lately (I believe the rise of the extreme right has a lot to do with this). In general, I am a firm believer emotional intelligence is in extreme short supply everywhere. We need to have more understanding how we should behave with ourselves and others. Society wise needs to change as well, but that is a tall order...

"I want to educate the next generation!"

Society: Oh shit, guess you'll be a forever renter having your empathy manipulated into forcing you to buy your student's school supplies.

"I want to run a hedge fund and send letters to the companies I own pressuring them to destroy their business model by giving their product/service improvement and employee bonus money to meeeee, and also fire the workers that made them so profitable for a short term stock bump, also for meeeeee!"

Society: get this man a private jet.

Our society lives in service to our economy, the opposite of the entire point of an economy. Our economy should tax and punish attempts at selfishness, and reward pro-social vocations that help society. No hope of that until collapse, but its sad to watch.

I always try to be nice, but the motivation comes in handy when the person in front of you seems to be trying their darnest to be infuriating

People do that here. There isn't a population center here where there isn't a massive tent city or cities within it.

In my opinion, a society where some people live in gluttony while others starve is worse than a nation where all struggle, because a society would divide resources equitably. We're worse because we have more than enough to feed, cloth, and educate everyone, but a few thousand sociopath families want to live like modern Pharoahs, that makes us a lot worse than a nation ethically that simply doesn't have enough food, homes, or educational resources, because impoverished nations don't choose to have a massive underclass as we do.

Getting ahead in a capitalist economy is more about birth lottery than anything, a few get lucky ingratiating themselves to the sociopathic monsters that own this system that we should be dragging out into the streets and letting homeless encampments, their greatest victims, decide what to do with, but our brand is supposedly upward mobility, and we're far from the top of that list in the world.