Yes, this is my problem with references to the ammo box. That exact rhetoric has been with us for decades now, and has in fact helped to get us to the point we're at.
Sure, maybe some ICE home invaders will be shot in self-defense while committing their crimes, but we already know how that plays out legally and even in the court of public opinion sadly (Walker/Taylor). So instances of self-defense won't change the big picture, regardless of such self defense options perhaps being pragmatic for those who are likely to be attacked right now or in the near future.
So that brings us back to the question of the large scale situation, which IME rests entirely on there being so many people Hell-bent on using the ammo box to "save" the country with the net effect of trashing it. We've essentially got flash mobs of brownshirts, understandably frustrated at how they've been disenfranchised and their liberties taken away, but having their frustration channeled into being part of the problem. Which I'd say comes back to filter bubbles, social media, pervasive and personalized propaganda, etc.
Of course freeing people from those filter bubbles is much harder than if we had managed to avoid the corporate consumer surveillance industry from taking hold and strongly facilitating them in the first place.