Russia is not entitled to swallow any neighbour that looks at them funny. Neither are we required to stand by and do nothing for the fear of the possibility that Russia will become more belligerent.

Russia thought the Ukrainians wouldn't put up much resistance and launched a war of conquest to prevent Ukraine from joining the EU. It's failed in it's gamble and it has to experience the consequences.

Russia often reforms only after military defeat exposes how badly the state and army are failing: Crimea pushed the Great Reforms, Japan helped trigger 1905, and Afghanistan plus the Cold War strain fed the Soviet collapse. Loss forces changes that peace lets the system avoid. And maybe we'll get a conciliatory government not an aggressive one doubling down.