That is the only way that Russia can win, so this is not surprising.
Russia already won in Ukraine. They have achieved their political (no NATO expansion) and military (seize ethnic Russian areas) objectives. That is a simple fact.
Any hope of Ukraine winning vaporized with the failed counter offensive in 2023.
Since then, the West, and with many political futures tied to this conflict, has been kicking the can down the road.
But you are correct in that Russia maintaining a nuclear arsenal with parity to ours is their only true deterrent.
The West enjoys such a large military manpower and budget, population, industrial output, intel service manpower and budget, technological advantage, that we frankly no longer saw them as a near peer and acted with impunity regards Ukraine. If the West truly mobilized and went to war, Russia would only have their nuclear deterant to stop us.
We’d say the same from our perspective as well. So would all the nuclear powers.