This makes me chuckle. The Bad Orange Man played the "insane king" role really, really well. Everyone was on their best behaviour until he left office. Peace talks in the Middle East progressed. Russia stayed in their borders. North Korea huffed and puffed and ultimately did nothing. Trade with China became more favorable to the US. It's almost like his foreign policy was effective.

To your point: Putin isn't nuts. He's just a really good politician. He's pragmatic and knows the value of being seen as "crazy" and "he might actually launch a nuke".