Much as I agree with the pacifist outlook, and avoiding conflict wherever possible, it's not necessarily about having "bigger guns", it's just about making yourself an unappealing target, where the risk of failure (or even the cost of success) is not necessarily worth it. It's no different to making your house unappealing to would-be thieves.
All else being equal, you're far more likely to get broken into with a flimsy wooden door, sash windows with crap locks and a post on Facebook announcing you're off on holiday for 2 weeks, than if you have locked double-glazed windows, multi-point locking door and CCTV all over.
I used to get bullied a lot in school, until my mum gave a very wise piece of advice - don't ever start a fight, but always make sure you're prepared to finish one; if someone hits you, hit them back so hard they never try it again.
Surprise surprise, it works. If someone thinks you won't fight back, you're an easy target, and they will do what they want. If they know you're prepared to fight back, then they'll think twice, and there's a good chance you might not even have to fight at all.
TL;DR; It's not about fighting back. It's about letting the other person know that you can and will do so if necessary.
Unfortunately, there's also a massive difference between fending off a "bad guy" trying to break into your house (where they face the risk directly) VS someone sat safely in a bunker on the other side of the world sending people he couldn't give 2 **** about to their death.