Have you ever heard of parochial altruism?
No?
It's quite simple, and explains a lot.
Parochial, simplified, means narrow minded.
Altruism is doing something beneficial to another, without gaining anything from the action.
For example, standing up to a bully when the victim themselves is too afraid to. Despite the risk of the bully turning his attention (and fists) towards you now, altruism is the act of seeing something you believe is wrong and confronting it on behalf of another person (or animal or plant, etc).
Put the two words together and you get something along the lines of "the act of stepping in on someone's behalf because of your beliefs, despite the risk to yourself". Even if there is no risk posed to you in the specific scenario, there might not be any benefit to the action either.
So if there's no benefit, and potentially risk, why do humans still do it?
One big example is vigilante's.
A vigilante is a person who takes matters of justice into their own hands when they believe the police and/or justice system have failed.
For example, if a horrible man kills a defenseless puppy, and the police can't convict him based on not having enough evidence, that would anger many people. And one of those people just might be angry enough to decide that "evidence schmevidence, that bastard drowned an innocent animal", and shoot the man in the head as his own version of justice.
We've all done something similar, though probably not to that extreme. Maybe something more simple and common, like seeing a rude customer berate a retail worker, and step up to tell the worker that they're doing a great job, and to ignore the rude customer. Or even seeing comments online harassing a user, and inserting yourself into the conversation to defend the user because you believe they are in the right based on what they posted.
We see this a lot in politics, with red versus blue, and this side against that side, religious people against non religious people, and even with online fandoms defending and attacking bands/actors/celebrities based on their own views and beliefs. No matter how big or small the scale is, people will always be willing to throw themselves into a battle of great lengths to defend what they believe is the truth.
I guess my point is that I participated in parochial altruism myself.
Though, if I had known what it would lead to, I don't think I would have approached that crying mother with her kindergartener son at the bus stop that fateful day thirteen years ago.
Because that was where it all truly started.
With a wide eyed little boy and his bunny tooth smile.
