Like I don’t know that, like anyone doesn’t know that.
Still noone, not the winning side, and especially not the losing side has any real incentive to launch them first.
It’s basic game theory, you never choose the option that has you lose absolutely everything, even if the alternative has you lose something big (like a war, or even your life).
Even crazed dictators like Putin know this.
And not even Putin can launch a nuke on his own. Even he needs generals and engineers that all know that not only they themselves will die if they obey, also their families will die, everyone they know will die if they obey.
We will never see full scale nuclear war, because noone at all could ever want that.
But Putin benefits from rubes just letting him bully everyone around him because, boo hoo he is so crazy and scary and after so many crossed red lines the next one surely is the one that makes him suicide himself, his wife, his daughter, his country, his place in history and anyone or anything he ever valued or cared about.