Posted by Yitz Grossman.
He must be greater in charisma, power, wealth, wisdom, and size.
The kohen gadol must be superior in these areas because it is a natural tendency to judge a person by external appearances, even though we know that this does not truly represent a person’s worth. Our Sages say, “Do not look at the pitcher, but rather at what it contains.”(5) Also the verse says, “Charm is false and beauty is worthless.”(6) Nevertheless, since people are impressed by external appearances, enhancing them can augment the kohen gadol’s effectiveness as a leader and generate the respect he needs to carry out his function.
Beyond influencing others, another reason the law requires these characteristics may be so that the kohen gadol considers himself worthy of the post. For him to be able to lead the other kohanim he must have ample self-esteem and be able to assert himself without feeling subordinate. If he lacks these strengths, this will become apparent to others and his authority will suffer. Eventually, he will lose his position of prominence in their eyes. Therefore it is crucial that the kohen gadol entertain no doubts about his capabilities, and so the law requires that he lack nothing.
The other kohanim are required to make him wealthy because the success of the kohen gadol benefits the entire nation. Without a capable leader there is chaos. The kohanim themselves will only feel comfortable when they know that someone is responsible for leading them. That gives them the assurance and support they need to succeed in fulfilling their own auxiliary functions. They also benefit when the kohen gadol can concentrate solely on his mission to serve the people and does not have the distracting worry of having to earn a livelihood. Therefore it is in their own interests to make the kohen gadol wealthy.