I think you miss one essential ingredient- Ukraine has no choice but to fight. The stated goals of Russia to denazify and demilitarize Ukraine and remove the government is hardly something that can be negotiated. Especially since it is clear Russia is going after the south and likely aspires to take Odesa and join up with Moldova. Ukraine is doing a better job of fighting than ANY western expert predicted- they assumed Kyiv would fall in a week and the chance for Ukraine to win would be an Afghanistan style partisan war over 5-10 years subsequently. The west didn’t predict Ukraine’s resolve so you can be sure Putìn didn’t either.

As for the currency fallacy, the Rouble strength is a sign of a problem and isn’t a positive thing at all. You can get an amazingly strong currency when imports drop to nothing but you still get export revenue, and you put capital controls and limit access to dollars. Meanwhile inflation is running at twice the rate of the west and whole industries in Russia are shutting down- as just no parts are available.

And Biden was right, though it is a bit of a cheap shot, he told the world Russia would invade and everyone laughed at him. I was speaking to my Russian friends even days before the invasion and they thought it was all postering but Putin to scare Ukraine, they didn’t believe it would happen either. But Biden doesn’t really need to remind people of this now.