If you replace "Russia" with "Putin" it's possible that he would rather end the world than lose in Ukraine. And it's possible that he would need to generate the escalation to justify ordering the ICBMs to fly, otherwise the commanders might decline.

There's a celebrity Putin created by propaganda who is a rabid foaming maniac, and there's the real Putin, who hasn't ever seemed particularly irrational, or even overly adventurous. There's also a war with Russia, a whole country, that a lot of people have sought to reduce to Putin, but as adults we don't have to pretend that Russia is an appendage to a single great man's will.

The real Putin isn't irrational, but he is fairly adventurous, launching wars for territory against smaller neighbors quite a bit (I think 5 times now.) But there is also the "Putin has terminal cancer" rumor, where he wants to reassemble Greater Russia or blow up the world trying, as he's running out of chances to shoot his shot.