That is a good question. If I think about it, I have no idea :). Somehow I got the impression that Bezos as the founder still holds a controlling amount of shares, but if he owned 50% of all Amazon shares, he would be the richest person by a large margin. Anyway, it seems that Bezos basically did not have anyone to answer to while leading Amazon - amazon reportet losses for many years for the sake of growth. That means he had a free hand to implement strategies, which are long term profitable. And I attribute the success of Amazon to no small amount to this.