This is a very terrible analogy. Nike is in the business of making shoes. A better analogy would be, why do Nike's customers' shoes fall apart after 1 year, but the shoes of the Nike executives last for several years?
Asset managers are supposed to be in the business of increasing their customers' wealth. However, most customer don't get as wealthy as the asset managers themselves.
It's as frivolous as asking why the executives of Nike have millions but the majority of people who buy Nikes don't.