nothing he is doing are the actions of sane person...
he's overextended himself taking this much territory, and doesn't really have anyone left to draft into his cannonfodder army to expand it further.
its going to take him years to put down the resistance in Ukraine, while dealing with heavy sanctions and shrinking resources. he just doesn't have the feet on the ground to go any further, and he doesn't have any feet left to conscript....if he moves men from Ukraine, that will embolden the resistance, and they will make major, harmful, demoralizing strikes...they know what and where to strike, it is their country after all