Anger can be misused in order to persuade, gain respect, punish, or intimidate
In spite of the relatively few times in life that anger is justified, many see anger as, if not the only option, the best option to get what they want. Whether it's used to persuade the customer service representative for the cell phone company that they'd better remove that $5 charge from their bill, or to make sure nobody disrespects them at their new job like they did at the last one, or to punish that family member for the rest of their life who mistreated them, in all of these cases, anger only ends up leaving more people hurt as a result.