In another perspective, it may not really have any justifiable reason. It just is like that. The amount of money people make really isn’t so “fair” or always directly dependent on the amount of value they produce for the company.
Things just are the way they are. Some people are better at negotiating their salary then others… Some people are given small loans of a million dollars to start them off :) . It’s not necessarily for any great reason.
If the CEO is a founder, they took the initiative first so that could be one arguable reason.