I don't think anyone is underestimating their efforts to stay in the war. I just think it's an ongoing sunk cost fallacy at this point on the part of the Russian leadership because it's clearly complete madness to continue.
If anything it smacks of absolute desperation to mobilise 300,000 people and start DESTROYING the infrastructure of parts of a country they say belong to them. What is Russia actually going to get out of this war once it's done, really? Absolute pariah status, a wrecked country full of 40million potential insurgents that would ENJOY -killing- Russians for dozens if not hundreds of years afterwards? A smashed economy, that can no longer do business with any country that isn't an authoritarian shithole?
To the average Russian maybe they don't care because presumably their standards of living will barely change there's so much corruption in tptb, but once the UK and Europeans sort out their energy infrastructure - and we will, we have a fusion plant being built and it really could be a game changer, and by this time next year alternative sources will undoubtedly have been built, we won't suffer forever - and then all these power games will have been for nothing.