Regarding your statement that "this approach doesn't scale well to the international level" and the associated implication that it does scale, at least relatively, well at the national society of individuals level.
Actually, I think the receipts are in, and they show this is 'bass ackwards' so to speak. A national society of individuals is not made more polite and less violent by being filled with better armed individuals. The good guy with a gun theory goes wrong more often than it goes right. In a state of assumed civil peace, the gun using criminal with an idea to use it will always have an offensive advantage over a gun owning defender who has one just in case but never knows the day and hour when they will need it.
But, although its a smaller data set, no nuclear armed states have attacked each other or been attacked with nuclear arms. Nuclear weapons were fired in anger exactly twice against a power that didn't have them in a globally endorsed war for unconditional surrender. Deterrence has worked for 80 or so years. Even if the number of nuclear armed states doubled, tripled, or quadrupled, we are still dealing with manageable and imaginable numbers of state actors, not the unwieldy number of thousands to millions of civilian actors we deal with in almost all civil societies. There are under 200 countries in the world, period. The great majority of them don't have any aggressive agenda or any hair-trigger paranoias of any sort. If they possessed a nuclear weapon, it wouldn't make them automatically adopt those psychological features/risk factors or desires.
A world of many nuclear powers may conjure up visions of some sort of nuclear 1914, triggered by some Sarajevo event, leading to world destruction, but for that to happen, the powers of the world need to be chain-ganged to each other in alliance commitments and with inflexible military plans that automatically commit them to launch off all their weapons inventories in a chain reaction once a local nuclear strike or exchange happens. But countries around the world are not bound by treaties exactly like those of 1914, and of the nuclear powers in the world, the only ones who have come close to having ready made plans (and arsenals) to destroy every potential rival in the world just in case, have been the US and maybe, Russia, all the minor nuclear powers have had a much less Schlieffen-esque, more sane deterrent policy, allowing their national leaderships to think about what they need to do. This whole idea is predicated on the premise that the US can restrain itself from doing anything insane on autopilot.
