I don't know what reddit is saying about Russia, but the "poor Russia, couldn't help themselves and had to invade" doesn't convince me. They made a calculated move which didn't go as well as they expected. It happens sometimes.

NATO had an "open-door" policy from the start. Russia knows this, so unless we really think everyone over there is really dumb, they knew that NATO's "sure, maybe we'll let you in sometime in the future" meant little. Ukraine was trying to join since the early 2000's and the reply was always the same... Ukraine wasn't going to join NATO in 2014, like zero chance. I recommend reading about the state of their forces, corruption, etc, at the time. What changed was that Yanukovych was going to sign the European Union–Ukraine Association Agreement, something that most of Ukraine supported (if we're to trust polls and look at the reaction when he unexpectedly changed his mind) while Russia wanted Ukraine to do the same agreement with them instead.

The existential threat... I don't know. Do you really think that their "existential threat" is now higher that Finland joined NATO (because of Russia's actions)? Estonia is fine, but Ukraine is makes that "existential threat" much, much worse? And who the hell is going to start a war in Russia when they have capacity to reply to normal attacks and will, without a doubt, use their nukes if invaded? Does NATO now have a death wish or something like that?

I keep reading about that non expansion promise... again, I guess you all think Russians are dumb and got verbal assurances thinking that it's the same as having them in writing. In any case, Russia doesn't own eastern Europe, many countries have made clear they don't want to be under their thumb or be part of their country. If Russia doesn't like this, well, though luck. A reality check would also help here... they're not the USSR.

The Vietnam example wasn't a good one, but my point is that if we start finding excuses to justify wars, well, we can, but it never ends and it's never our fault.

The US has some history with Cuba... but the only time when there was a really serious reaction wasn't when Castro became friends with the Soviet Union... it was when nukes were deployed in Cuba (partially their fault, after deploying theirs in Turkey). Russia invaded Ukraine because they were winking at the EU and NATO... like, they didn't even kiss!

I know why they invaded, but I also believe in taking responsibility for one's actions. We can talk about moral responsibility, but at the end of the day Russia invaded Ukraine and therefore they are responsible for the war they started.