> I am not really worried about Germany, South Korea, Japan or Taiwan armed with them.

You should be. The more small states with nuclear weapons, the more chances there are that any one country feels like a nuclear assault could be "worth it". Heck, just look at India and Pakistan. I can't remember which Indian government minister said it, but years ago he essentially said that India could "absorb" a nuclear strike from Pakistan, because since India is bigger with a lot more people, any nuclear volley would mean the complete annihilation of Pakistan while India would "only" lose a couple hundred million people...

The more proliferation there is, the higher the chance any one government will move away from MAD theory to "well, guess we've got nothing left to lose".

The more independent entities with Nuclear weapons, the more avenues for one to be used. Simple as that. Every country has potential to move towards national fanaticism over time.

That's just not the case. Look at every conflict of the past 50 years. Major powers trade very carefully against a nuclear armed nation. Which by the way largely explained Biden's tepid military support to Ukraine, giving them just enough weapons for them not to collapse but not enough to make any serious dent to Russia. And basically maximising casualties by making the conflict last.

That's not an argument against my statement, IMHO. If I were a nation without Nuclear arms, I would absolutely be racing to get them. That's independent of whether or not I think the aggregate risk increases. The US and Russia have deep levels of communication that have evolved over time in responses to near misses with Nuclear weapon firings. The more countries that enter in to that territory, the more need to have that communication and the more chances and avenues there are for mis cues. One mis cue results in at least one nuke being fired, and where one flies several have the chance to. And that's ignoring the fact that fanatical / suicidal regimes do in fact come to power from time to time.

I too hope that more nuclear arms will result in reduced conflicts and a reduced risk model overall. But if I were to bet, I'd bet that if we 10x the number of players with Nuke's, we 10x the number of chances for some to be used.