What is the cause of verbal abuse?

* There are many causes for verbal abuse. Some people have grown up in the environment of a verbally abusive parent or parents and the chain continues in many cases onto the children (learned behavior); a person who feels they are insufficient in the eyes of society and have not succeeded; a person that has had a lot of bad luck and feels they are judged by their peers; a person that hasn't had the opportunities others have and feel cheated; lack of confidence; over-confidence to the point of having a high ego within themselves and they feel other people don't stack up to what they feel is on their intelligence level; medications can cause a change in personality; different diseases can change a person's personality; Alzheimer's and Dementia (sister to Alzheimer's) can change a person's personality as well as traumas such as rape, losing a loved one to murder, physical or emotion abuse including partner physical and emotional abuse.