"Idealism", which unfortunately underpins all mainstream political discourse, is simply that certain actors (people, states, etc) are good because they're good or they're bad because they're bad. It's really the Marvel view of the world. There are good guys and bad guys. Idealism is a completely inadequate way to view the world because it simply reflects the propaganda that's effectively sold the idea of who the good guys and bad guys are.
"Materialism" is a broadd term that originates in the philosophy that people affect the material world and the material world affects people. More specifically to this point, it's the idea that people do things for a reason. That doesn't mean the reason is justified or sound or good. But there is a world view that underpins any actions by any actor.
So when it comes to wars, the idealist will say one side are the good guys and the other side are the bad guys and never go any deeper than that. The materialist will derive that all wars come down to the desire for resources and land. Not religion. Not ethnicity. Those are simply pretexts to motivate the citizenry and foot soldiers.
So Putin dons the Duganist [1] hat, just like European kings in the Crusades wrapped themselves in Christianity. Putin may even be a true believer but that's not why he's doing what he's doing. He's securing a land bridge to Crimea, a warm water port on the Black Sea and control of territorial waters in the Black Sea and the resources contained therein.
He probably figures the West will eventually lose interest (which is already happening) and in the mean time he can keep selling oil and gas to China and India so the sanctions are inconvenient but can be weathered.
There's nothing crazy about it.
But even if he was crazy, to launch a nuclear attack, someone would have to carry out those orders. Bomb loaders, generals, submarine commanders, pilots, missile silo operators, etc. Look up the history of Vasily Aleksandrovich Arkhipov.
And yes, he absolutely is the type of person who would destroy something if he can't have it. He did it with Grozny, he did it with Mariupol, he did it with Bucha, he did it with Bakhmut, he did it with Avdiyivka, and he will continue doing it with the rest of the world. So far, he has sent hundreds of thousands of Russians to their death, and they continue to do it. There are literally thousands of Russians that know they're gonna die, and they do it anyway. Your belief in the humanity of people running nuclear bunkers is already betrayed by their own actions in every conflict under Putin's watch, and somehow you think 100% (because it only takes one person!) out of the 3000+ nuclear silo operators will suddenly grow a conscience when Putin tells them to send the missile. It's fucking absurd.
Vladimir Putin is exactly that kind of person. When backed into a corner and knowing he will die, he would rather nuke the whole world than accept his fate. And those orders will be carried out by people in heavily restricted information silos, who only have the explanation of their commanding officers as reasoning. For all they know, this is a test, or the US already has launched their nukes, or if they don’t launch the nukes their mom will be dropped out of a window.