As much as most folks don't like to hear it (which is a VERY GOOD thing, because that means most folks are middle of the road normal), required extreme measures are taken usually by those who have lived at one time or another under extreme circumstances (good or bad). Societies of the world are NOT focused around raising rash or especially calculating, reflexive individuals. They want moderate people who respond meekly--if at all--the ideal that they instead turn to those in authority.
Imagine a world where everyone responds with their first impulse...and because of that children are raised to be even more reflexive/instinctual and rash just to compete. So, it's pretty clear why it needs to be the other way, and why our world is designed so in normal times those qualities aren't needed.
The reason most folks don't like to hear that is, they like to envision themselves as suddenly having the wherewithal to respond to any situation as needed...naturally in situations they will never face (going back to my original post about preferring not to read about real world circumstances). The fact of the matter is, they have been CONDITIONED over their entire lives, from all sides, to NOT respond that way. So, if a story situation 'requires' instantaneous, unrestrained, unreasonable rage to just barely survive it as an example, most folks in truth would fall short.
People who have had hammered into them from birth to heroically rise up when needed, are as psychologically unsuitable (perhaps even damaged) to cope with normal society as those who suffered at the other end of the spectrum. That's what what the military tries to drive into their combat soldiers in a compressed time-frame along with restraint (which grays the lines). If they see no combat, then it usually results in a responsible, self-regimented individual which is all a plus. Put them into extreme combat long enough, however, and it becomes very difficult for that person to cope in typical society since you're asking them to instantaneously dump years of training and experience.
Finally (to not drone on like I do), in common terms, a person usually can't take a punch unless they're used to being punched. Boxers aren't taught just how to hit, they're taught how to take hits. So it goes for people facing extremes. How many of you know of someone who succeeded all their lives, to abruptly lose it completely when they fail one time? More so, how many times have you heard how when X-person is assaulted, robbed, faced a violent death...whatever...how that broke them? But, someone who faced that often throughout their youth, now when faced with it either endures, rises to the moment, and after bounces back.
K2