I would like to remind everyone here about something. WWII officially started for the US with the bombing of Pearl Harbor, that is true. But the Japanese attack on PH was actually a response to the US cutting off their oil supply and essentially hitting them with a trade embargo and economic sanctions after they invaded China. They needed oil for their war effort and thought that they could scare us into trading with them again to avoid a war by attacking Hawaii. They miscalculated. As soon as we declared war instead, they knew they had messed up by opening a new front without having the resources to do so. There are several quotes from Japanese generals after Dec. 7 that all essentially said, "We won this battle, but have already lost this war".
Just a reminder that economic sanctions are actually hurtful. I agree that Putin doesn't give two craps about it, this is an existential fight for him. But I think the current sanctions are an attempt to make life very uncomfortable for the common Russian citizen, and for the oligarchs surrounding Putin. The hope is that they will know who the real enemy is here and turn on him. If they do that, this all ends. It's the best way out, in my opinion, and is what we are likely strategizing for.
The minute the EU cuts off all oil and gas trading with Russia, Russia sees it as an escalation (like Japan did) and this gets worse, not better. We will probably eventually do that if Ukraine falls. But in the meantime, this is not about saving Ukraine, it is about stripping a madman of his power in a way that hopefully doesn't draw all of Europe into a horrific war. The best way to do that is if the Russians themselves take care of the problem.