Ukraine

I can't imagine a scenario where shooting a nuclear warhead at your neighbor wouldn't also make for a very bad time for yourself. If the radiation killing your own army wouldn't be enough, the second a nuke is launched everyone else is going to launch them. And I don't think with the trouble Ukraine is already giving Russia that WWIII would make for a better time.

Also it would be the ultimate "if I can't have it you can't either" as little will be left afterwards (assuming they launch several to try and cover as much of the country as possible).

What about the consideration of having one's whole country reduced to ash and radioactive glass? Are they factoring that into their considerations?

Some citizens want theirs countries to be perceived as good, pure. Example: US has full ranges of issues that can make it consider to be a bad country. But its citizens wants to sell it as the best/ purest country in the world. Chant with me USA,USA USA USA. Russian citizens on the other hand has a bad country and they want it to be perceived as your worst nightmare, the country that keeps you awake at night. Hence the normalization of nuclear threats, those threats are for the western world people that are living comfortably and have more to lose. If you are barely surviving in your country do you really care about the end of the world while you can take with you some rich countries?