I don't believe I am naive. I can see that Putin is a strongman. But if you study up on your history and actually read about Hitler, you'll see there is a very different pattern between the two.

Hitler was a successful revolutionary who liked to think big and take even bigger risks. The more extreme the plan, the more he liked it. He genuinely hated the people he was persecuting and laid all those those out in his writing.

Putin is a patient plotter and a rationalist. He probably resolved back in 2014 after the Ukrainian coup to do something about it, and it is clear he has been preparing for the possibility of this war for years.

There absolutely was an opportunity to mend relations. Obama tried back in 2008 when he was first elected and warned of the danger of pushing Russia too hard with NATO. Trump tried when he was elected and was thwarted by the permanent, unelected security state at every turn. American presidents are only nominally in charge of these people, and they have their own agendas.

As for what Putin does after Ukraine, I do not believe it involves any more European invasions. Everyone in power in the West capable of a little introspection and independent thought understands why he invaded Ukraine. If he went for another European country, even a non-NATO country, he would prove your argument to these people and they would act directly just like with Hitler and Poland, leading to WW3 and Armageddon. He knows this, and so do Western military thinkers.