It’s emotional immaturity, like you said very childish.

Narcissists are deeply emotionally immature, in a way that is incredibly resistant to healing. Their entire life narrative and every action is based on a fundamental delusion. Most of us struggle with change and admitting when we are wrong… To heal, a narcissist must change their entire world view and admit they have been living a harmful lie their entire life.

It’s quite bad when such a person gains significant power and has goals that conflict with well-being of others.