From The Power of Words by Rabbi Zelig Pliskin p. 93

Some people insult others because of their will to dominate them. Even if they seem devoted to a cause or a responsibility, that is not their main motive in wanting domination. They want the feelings of strength they derive from seeing people become submissive before them. Those who have this tendency have an essential lack of respect for other people. They are not concerned with the individuality and dignity of others. While people who have this tendency differ greatly as to the degree they have it, anyone who has it even in small amounts will frequently violate the prohibition against onaas dvorim (hurting others with words).

The problem here is that people who strongly want to dominate others are usually not motivated to give up this power. It is crucial for them to learn to feel greater respect for others. This will enable them to speak in ways that will not constitute onaas dvorrim. True domination is when one has domination over one's own impulses. This awareness will prevent a person from mistakenly trying to obtain feelings of domination by putting others down.