If you recall, destroying and occupying Germany cost 25 million lives and six years of war.
How do you envision that happening? And what do you think Russia would be willing to do to prevent that outcome?
Most of those lives were Russians grinding against Germans. Russia is already now a pariah. Using nukes will ignite the rest of the world to destroy them: by nuke or otherwise. Hopefully not a protracted world war.
Russia will be gone in any case. What to do with them once they’ve lost?
That is in fact, the US policy we have been following for most of my life - to balkanize Russia.
Only we get to be a superpower. No one else.
Mackinder, Ziggy, and the Rand report are good reading if you don’t believe me.