Imagine kid A studies really hard during his youth and doesn't get to have any fun because he's working so hard. Kid B likes to slack off and party and do drugs. If Kid A grows up and makes it big, why does kid B deserve half? Why should he deserve any portion? You could tax kid A's wealth but you can't tax kid B's youth and pleasure. Why put a cap on on kid A's wealth if you are not putting a cap on kid B's leisure time? We put no such caps on anything else whether it be beauty, intelligence, number of friends, popularity even though all of these things cause disparity.