When a person is humble, the rest of his character traits naturally fall into place. But when a person is arrogant, the rest of his midos are out of balance as well. An arrogant person becomes angry easily. A humble man doesn’t. An arrogant individual doesn’t feel the pain of others, but a humble man does. The pivot point of all good midos is humility.
Just as humility is the center of a person’s character development, so too is it the cornerstone of his avodas Hashem. The Chovos HaL’vavos explains that just as a master needs a servant, a servant needs a master. One cannot exist without the other. Any sense of arrogance is a denial of my dependence upon Hashem. It revokes my status of a servant of my master.
This sense of dependence upon my Creator brings a person balance and internal happiness because he is in synch with his himself. He doesn’t need to self-inflate and create illusions about his worth. Ultimately, it leads a person to success in this world and in the World to Come.