Aggressive and violent bullies with reactive egos have almost always experienced severe hardships when they were little. They were abused, neglected or abandoned.
Tiresome, nagging and selfish jerks probably didn’t get enough love and attention when they were small.
Those who experienced an abundance of love and attention when they were small children have seldom ego problems as adults.
Ego is, from this point of view, a marker for how much love and attention you experienced as a child.
However, some people have experienced incredible hardships when they were small but grow up and become very warm and friendly as adults. And many of those who experienced an abundance of love and attention when they were small grow up and become like spoiled brats for the rest of their lives.