And in this case the US participation should come. Wouldn't be better to fight a Putin's Russia that was weakened in Ukraine? Perhaps weakened so much, that Putin's won't attack at all. Perhaps weaken so much, that the US can scale down its European military force deployment (saving money) and concentrate on other things (China).

So yeah, US investments in Ukraine directly benefit America. Ukrainians are fighting for Americans. So much so, that they are destroying Russia's nuclear weapons capabilities (destroying radars, strategic bombers, submarines and ships, weapons arsenal, ballistic rockets, carriers of nuclear weapons like Iskanders).

I’m not following your point, or maybe you missed mine. You said 100,000 Russian soldiers dead doesn’t make the US any safer, and I agree, but it does make Europe safer because there are fewer Russian soldiers. But then you compared the population of Russia and the EU to imply that Russia is no threat to Europe.

But that analysis is flawed, because the population of Europe isn’t one monolithic block that is guaranteed to respond to Russia with military force in such a way that a direct comparison of the numbers makes much sense. For example, what I mentioned already.

And your reply was Ukraine is not in the EU.

??