This is a lot of speculation on what exactly Putin's calculations were. Of course war is bad for Russia in the short-term but given NATO encroachment, you can't just let yourself be slowly encroached on forever.

I think your point about countries that were typically neutral becoming not neutral is an incredibly important data point here. Though I read it in a different way. Specifically, the fact that Switzerland became partisan (Switzerland!) seems to really support what Mearsheimer was saying (i.e. support for Ukraine by the west is much more about financial incentives than standing up for human rights). I mean, did Switzerland, who was neutral even in WWII suddenly gain a conscience now? (Though I guess another way to read it is just that Switzerland feels very safe at this moment to be partisan, or that power dynamics have shifted significantly in Europe in recent times.)

But anyways, let's just take a step back for a second... it's clear that the US empire is much more powerful than Russia at this point. Of course if the US decides to back Ukraine with a lot of resources and support, it's going to be a struggle for Russia. The fact that it's a struggle does not seem to say much.