But in a mass shooting scenario those people are in a life and death situation by the actions of a suicidal maniac and they are in need. And there is a chance that one or more of those persons could be one of your family members, maybe a brother or sister, or mom or dad, niece or nephew, aunt or uncle. And simply based on carry statistics I know that not everyone of them carries everywhere, everyday. Wouldn't you want someone to come to their aid if ever needed? I know that if they were my family members and an able bodied, trained, armed citizen was around I'd be mighty grateful that they stepped up and helped if they could have.
And no, you shouldn't seek out to help everyone the comes your way, after all superheroes are fiction. But in those rare and dire circumstances that we all hope don't happen to us if an able bodied, trained, armed citizen was around, and could have helped, and turned their back on those people that is simply unconscionable. Period.