'But just because I think that way doesn't mean others have to as well.'
If you don't think that way you're wrong
Like those two guys who witnessed the girl in NY in trouble and didn't do anything but notify police. The fact that they called for help says they have a conscience and they did the right thing by doing that, but they should have done more. Nobody is asking for heroes but it is your 'duty' to do 'all that you can'. And I don't think they did all they could have and should have. I'll assume those guys 'froze' in fear.
Why, because someone trains in martial arts, does it mean that we have to be supermen and defend everyone? Hey, if someone chooses to get involved, thats fine but I don't think that anyone is required to. Simply calling for help, providing the police with a good description of whats happening, should be good enough.
Think about this...how many times during a domestic disturbance, do we often see the cops get attacked by the very same woman who was getting beat up by her husband? It happens. Suddenly, depsite her getting her *** kicked, now she loves the guy, doesnt wanna see him in jail, etc. Same thing here. We don't know who the people are, if there're weapons, etc.
I think that by always looking to get involved, that kind of hints at the person wanting to be a hero.