Here's what you're missing: there was no serious movement on peace talks until we dug in.

I'm not missing that. There's still no serious movement on peace talks that might be acceptable to Ukraine, one of the combatant parties. The only reason peace talks are "moving" is because the Administration has floated the idea of giving up the conflict and letting Russia win all of their objectives in the war (and taking a piece of Ukraine's resources for ourselves). We're not really bringing much to the table by walking in with the suggestion to Ukraine, "Russia would stop killing your soldiers if you just gave in to the invaders and stopped defending your country."

No. The Europeans had 2 rounds of total continental war in the last century and they don't want that anymore.

They didn't want it then, either. It's not like everyone planned for WWI to happen. If you walk back from the modern collective security arrangement

Again: No. You used the word "Collective". Right now the US is the sole guarantor of Europe's security because the Europeans are barely investing in their own defense.

Here's a fun fact - the non-US members of NATO spend more on defense than China. Nearly as much as China and Russia combined:

en.wikipedia.org - Military budget of China

Again: you keep imagining a Europe that doesn't spend much money on defense. In reality, NATO outside the US has the second largest military budget in the world. They only look small next to the U.S., because no one spends like the U.S. But they spend more than China or Russia or any other country on earth, save us.

Your notion of a massively armed Europe out bashing each other or threatening the US is unrealistic: to arm up to that level they'd need to tear down their social support structures to pay for it.

Nonsense. They don't need to build up their military to US levels to start bashing each other. They're all wealthy by global standards - wealthy enough to develop militaries that rank among the world's largest, if below the super-power level. More than enough for brutal and destructive conflicts.

Mississippi, the poorest state in the United States, is close to surpassing Europe's largest economy Germany's GDP per capita. Euronews Business compares US states with European countries.

Yeah - same is true of China, whose per capita GDP isn't even a third of Mississippi's. Yet I think you would agree that they present the pre-eminent threat to the United States in the entire world. Collectively, the EU's GDP is larger than China - and their GDP per capita is more than double that of China. So yes, they're wealthy enough to militarize.