You can be forgiven however if you're a millennial (as I am) or younger, because the long peace has been so long that it seems crazy that Russia might start dropping bombs, say, on Copenhagen or London. "They wouldn't dare attack NATO" we would have said 10 years ago. But today, NATO is at risk since too much of its credibility is tied to the US and the US is now unpredictable. With one stroke of an "executive order" pen the US could just call backsies and pull out if one man considers it politically advantageous to him to do so. That has been unthinkable for 75 years and now it's just reality.
Russia is a lot less afraid of Western Europe than they were/are of NATO. Would they win? IDK. But my perception is that the very notion of war would shock the s**t out of the 20-somethings that Western Europe would need to conscript in order to fight an all-out war. If too many refused to fight, Putin might just roll in there relatively unchallenged.
Note: US civilians are certainly not any more ready to enlist than Europe's! But the US is the only Western country with (almost) enough people already enlisted to be a credible threat in a major war.