If something happens (and it likely will) we, as a nation, and as individuals, will have to deal with it. Prepare to the best of your abilities, but understand that in most scenarios, it won't be enough.
Should we then, crawl under our collective beds and await the destruction, cowering in fear and wasting our days? I can't stop some madman from poisoning the water supply or setting off a car bomb outside of a popular club. All I can do is live my life. That is what I chose to do. I will exercise appropriate caution and will take appropriate measures to protect and provide for my family, but there's not much I can do to stop a random, terrorist attack from killing me or any member of my family. If I am to die from such an attack, I will do so living my life to the fullest, not hiding in my basement.
As for your last statement, if there was a disruption of life as you describe, and if your neighbor came to you for help, would you gun him down? Would your darker side take control?
Believe me...Darwin was RIGHT...survival of the fittest...I have NO obligation to help a neighbor when it is a life and death sitution...IF I PREPARE for hard times...and "they" didn't...big ol' case of tough shit! Yes..IF my property and supplies are threatened...don't kid yourself I'd shoot their asses in a New York minute...and ohh...BTW I also own a cross bow...and IF...BIG IF...I run out of bullets...don't think I won't have the time to whittle arrows if need be...