The U.S. and Europe doesn't need Ukraine. As you point out, Russia already took control of Eastern Ukraine and Crimea and no one did anything. What the U.S. can't allow is becoming sidelined (as it was during WWII but took a while to realize), so it ultimately can't allow Russia to win Ukraine. But it doesn't see it yet.

Trump and Biden both suffer under the same delusion--that the U.S. could push Russia out of Ukraine if it put boots on the ground and unleashed its F-35s. If it was ONLY Russia, the U.S. would have a shot but it wouldn't be ONLY Russia if it came to that.

Trump et al are classic bullies in that they believe they're strong because they've beat up some small fry but don't recognize the small fry, if they band together, or get the help of others, can overwhelm the U.S.

Russia already made that miscalculation.

Everyone believes they're stronger than they are: US, Russia, China, Europe, etc. India knows its not strong but understands when the big dog fights they can get the bone ;)

It seems we pretty much agree on the broad strokes. I don't believe Russia can win against the U.S./Europe, but this is just one part of a global war. So I'm not saying the U.S. will win. It may. It may not. There's a long road ahead before we can tell what that might mean? The next stage is for the U.S. to get a bloody nose. Russia has already wrestled it into the mud. That isn't enough to wake most people up. Make sense?