The question I don’t have an answer for here is how does Russia control Ukraine if they do win militarily? It seems incredibly unlikely that they have enough troops and doesn’t seem remotely sustainable.
It only makes sense if they only planned to bomb Ukraine into handing over Donetsk, Lukhansk, recognising the loss of Crimea, and agreeing not to join NATO.
From this perspective, it's hard for Russia to loose. A destroyed Ukraine won't fight for their lost territories and won't be accepted into the EU or NATO.