As a hypothetical -- Russia does invade Ukraine and the Western forces offer substantial but indirect military support. Russia strikes at a supporting NATO military installation just metres over the border in a NATO country, on the assumption that NATO will not respond to that as an Article 5 attack on their territory. But they assume wrong.
Consider how the Japanese assumed the Americans would be amenable to sue for peace after Pearl Harbor at some point. They had a mental model where it was risky, yes, but rational. But they deeply misunderstood their enemy. History is full of this pattern.
I don't see how is that relevant in the case of Russia though, they have little to gain and a lot to loose from any war with NATO or invasion of any NATO countries and so far Putin or anyone did not indicate in anyway that they think otherwise.
Always the first misstep.
Geopolitically it made sense for the US and the West to largely ignore it. Due to their military presence there no one could argue that it wasn't Russia sphere of influence anyway. It was a small price to pay for ensuring that the the rest of Ukraine would shift it's alignment from Russia to EU/NATO (not having a Russian fleet stationed in one of your ports would likely make this move easier).
None of this in any way applies to the Baltic States.
I can't speak to the will of the Russian people, but anti-western propaganda has been common there for well over a decade. If it's even been marginally effective they may be more geared up for conflict than people expect.
Would you ask what rational reason China has to invade Taiwan?
From a more cynical, pragmatic "realpolitik" perspective one can view Russian actions in Ukraine as largely defensive. From the collapse of the Soviet Union Ukraine largely functioned as a semi-protectorate of Russia, even before 2014 Russian probably had significantly more troops stationed in Crimea than Ukrainians themselves since their black sea fleet is stationed there. After the events of 2014 Russia saw that long-term they are likely going to loose Ukraine anyway and basically decided to cut their losses and at least maintain the control of Crimea. It's not like Russia actually wants to fully annex the regions in eastern Ukraine their currently fighting over, they just want a semi permanent conflict which would destabilize Ukraine politically and to ensure that the Ukraine could never join NATO (and likely the EU), since NATO accepting Ukraine would be basically equivalent to them declaring war on Russia..
What you say about the Russian actions in Ukraine is true, the question is would they prefer full annexation if they knew NATO wouldn't intervene? I'd say they probably would. If the goal is security, not many things more secure than saying "this is our territory now", it would also enable a lot of direct control instead of relying on manipulated chaos that can always blow up in your face.
>prefer full annexation if they knew NATO wouldn't intervene
You mean of the entire Ukraine? Because it would cost them more than it's worth. No Russian actions since 1991 have so far indicated that they actually want to conquer any foreign area not inhabited by a Russian speaking majority or whose population would be likely to actively resist such occupation.
Stirring up ethnic border wars is a cheap way of sapping the strength of regional powers. The British Empire honed it to a fine art.
Russia largely doesn't care about people as much as about territory.