Russia’s Putin apparently believed (a) if he invaded Ukraine it would roll over and play dead, putting up little resistance. He also claimed to believe (b) Ukraine’s citizens were indistinguishable from Russians.
Yet he knew Russians have a long history of resisting invaders. If the people of Ukraine were much like Russians, why wouldn’t they put up the same sort of bitter resistance to invasion?
Beliefs a and b could not both be true, as Putin has learned the hard way. He has taken a firm grip on a tiger’s tail and the tiger is angry. The only way to survive that situation is to kill the tiger, and it isn’t clear he has that ability.
Putin's only personal way forward may be escalation. That is not, however, Russia’s only alternative. It isn’t clear if Putin can get Russia to follow him on a succeed-or-die-trying path.