What would make him desperate enough to sacrifice the entire current and future of Russia? Losing an invasion of Estonia?
When you are 70 years old, spending half your life revered as a great leader of a nation, you would be desperate not have your historical legacy ruined by losing a war and possibly your status and pride in your final years.
I'm definitely of the opinion that this would be an unlikely scenario, but then, are you willing to bet the future of the planet on a hunch that a single person that you don't know personally is actually not unhinged and desperate?
I don't know about you, but I'm personally going to avoid betting on anything that has a mere 1% chance of resulting in nuclear winter.
The scenario that we have been discussing is NATO's response to a Russian invasion of a NATO member such as Estonia. What are NATO's options?
1. Full scale (offensive) war. They attacked us, we will end this in Moscow 2. Repel the attack, take no aggressive action beyond what is required to come to a stalemate 3. Do nothing
I have argued elsewhere with you that I don't see 1. as being at all likely due to NATO's goals, defensive posture, and military superiority.
Doing nothing would only embolden Russia and destroy any pretense of an alliance at all. If not in Estonia, when would NATO intervene? Poland? Germany?
Thus, repel the attack and take no aggressive action. De-escalate and give options for Russia to save face.
We don't have to bet that a single person is not unhinged enough to press the button. There are command and control limitations purpose-built into even Russia's nuclear arsenal. Putin also wouldn't want his historical legacy ruined by the thorough destruction of the present and future of Russia. I'd go further to say that he knows all this, and wouldn't invade a NATO member in the first place.
I hope this is not how nuclear strategy and tactics is prepared. If sane people are in charge, retaliations will be proportional and exchange will be limited.
Russia obliterates Katowice, one of several countries obliterates Volgograd. What is the next move? You just ended the lives of a million of your citizens. You just stop there?