If you are, or consider yourself, part of the top "performers" you have a self-interest incentive to favour this because you expect to be among the "winners" an

If you are, or consider yourself, part of the top "performers" you have a self-interest incentive to favour this because you expect to be among the "winners" and don't want to share with the "losers". I.e., unequal earnings distribution looks better and better as you climb the social ladder because you benefit more and more. On the other hand, if you are at the bottom you may strongly support more equal distibution because that can only benefit you. Same reasoning as to why workers unions emerged from the bottom, not the top.