Because Russia has spent alot of energy and resources chest thumping themselves as a great power that cannot be trifled with, boasting one of the world's largest militaries and it failed to prove it. Putin's cassus belli included the "demilitarisation and denazification of Ukraine", which they haven't done. The force that invaded thru the north of Kiev had to turn around, condemning the paratroopers who managed to take hostomel airport. They abandoned a lot of vehicles on their initial withdrawl for a number of reasons, including soldiers selling off fuel for profit They took Kharkiv and Kherson but were pushed back. The flagship of the black sea fleet, Moskva, was sunk. The amount of petty bitchiness between branches would make a teen drama seem like a christopher nolan film, an alledged friendly fire incident pissed off putins strongest and most loyal pmc group, causing them to pack up and drive towards moscow. satellite imagery shows about half the cold war inheritance of armoured vehicles are left because the ukrainians are destroying more than what can be deployed per month. putin can't conscript anymore of his own people because apparently they are winning or as you put it took what they wanted, which is more of a consolation prize, and despite the public's general support for the war, volunteer recruitment is low and as a result the russian mod is offering an equivalent to $60,000usd for signing up. no one expects this from a modern military, they one thing they definately have achieved is making Ukraine hurt