And if they now think that way, what will it make USA think, or the UK, or France?
It's called a 'preemptive first strike' for a reason you see, where your hierarchies will be all too busy to find the time to confer with you, before it.
You can look at this way. If they want to defeat not only Ukraine but also the West, their best bet should be nuclear, a first and then possibly that second strike. Where USA will be a primary target. If they think of it as a primary European sandbox, but why should they do that? Doesn't make sense unless they get a promise of non involvement, from the same nation most involved in destabilizing their country and current hierarchies.
But it's correct in that Russia by now has a battle hardened military force, even if they didn't in the beginning. And with us sending more arms telling Ukraine to go all in, a 'world war' is just around the corner. Whether Russia decide to stay conventional in such is another question. We can't stand seeing our bets fail, can we? So much face falling off.