> You can't allow an adversary to take what they want and win every battle "because they have nuclear weapons" without capitulating world domination to that adversary.

Strawman. Ukraine is not in NATO and is thus forced to keep neighboring Russia happy. That's just realpolitik. US can not and will not retaliate as that would be WW3. On the flip side, Russia will not attack NATO countries as that would also be WW3.

The only real losers here are primarily Ukraine which is being destroyed and Europe which has to keep doing what US wants since it's dependent on the latter for defense.