I think you severely misunderstand Russians. They aren't western. We in the west routinely make the mistake of assuming everyone is also western or at least wants to be western. But this simply isn't the case.

Sure, there are some more liberal, high society, global citizen, type Russians... But by and large, most Russians are down to their bones Russian. And hardship is something that's deeply engrained into their culture. The harder things are for them, the more resiliant they become. It's just part of their identity and culture. A group of people who have an enormous border that historically was always in a state of conflict, being betrayed, invaded, oppressed, and so on... I can't emphasize enough just how much Russian people can tolerate hardship.

Further, I think you have a misunderstanding of their loyalty towards Putin. They genuinely do love that guy. They LOVE a strongman, and are extremely patriotic to the point that even Americans would think it's a bit ridiculous. Again, there is just a lot of historical identity tied around this. They view presidents who don't rule with an iron fist as weak and vulnerable.

Finally, the Russian people themselves feel like this is necessary. This genuinely isn't just Russian and Putin propaganda brainwashing the citizens. The citizens themselves feel like their borders are being encroached on, and it terrifies them. They do not, under any circumstance, want what they perceive as a powerful group who's betrayed them, directly on their border trying to influence everyone around them. This is existential to them to keep adversaries away beyond even arms reach. You as a western may think, "Pshhh but NATO is a defense alliance! They have nothing to worry about!" Well Russian's don't see it that way. Everything is one way, until it isn't. Things can change very quickly and rapidly and the last thing they want is to have welcomed in a critical vulnerability at a key geographic location. Mix this all in with also Ukraine having deep cultural and historic connections, it's like watching Canada ally with China... The US simply wouldn't stand for that any more than Russia would stand for Ukraine allying with the west.

And I understand your point on how we can't allow this "Age of Empires" going on, but they don't care. It's hypocritical of the West to enforce that "rules based order" which we ourselves routinely violate. They actually would probably be okay with this order, if it actually wasn't one sided. But all they see is the US constantly overthrowing regimes they don't like, using shaky justifications draped in empty claims of virtue... So it's a meaningless rule to them. I mean as we speak the US is supporting defacto annexation in Palestine. So again, Russia isn't going to take those claims seriously that we can't violate borders any more, when the US hypocritically does it themselves all the time.

And no, I dissagree on your assessment to think that the USA thought we could get Ukraine through Russia's initial onslaught then lead them to victory. Our own DoD leaks and assessments made this very clear. We assessed that Ukraine can't possibly beat Russia in any scenario. Not a single war game has Ukraine winning. None. Even with our miscalculations on them, they still have everything in their favor. I think our conclusion was the best case scenario was an indefinite stalemate with no viable resolution. So basically an indefinite forever war was our best case scenario conclusion.

Hence why I believe, especially when you look at our actions, that our goal was not for Ukraine to win, but for Putin to be killed. It's why we levied extreme sanctions, and pulled every card we had in the book against Russia, to the point that Biden himself called for Putin's head on live television. Those statements aren't gaffs. Those are signals to covert players what our goals are. It's why Putin wouldn't let even his closest generals come within 20 feet of him. He knew he was a target and had a straight up butchering of all sorts of elites and personal, to ensure his safety. With our last ditch scenario of the failed coup with their private military.

But ultimately, coming back to what we were speaking about, that's what sort of situation we're in. It's not so much how we view things in the west, but how Russians view things in the East. Their perspective of the conflict is all that matters when assessing how far they are willing to go. No amount of virtue and moralizing will change how they subjectively feel about things. And how they feel, is they will fight this until Ukraine completely runs out of men. They've made it clear over 2 years ago that this is now a war of attrition, and they will ride this out for years until Ukraine can't possibly continue. They simply don't have enough men to keep this going indefinitely the same way Russia does.