Capital accumulation. Whoever takes the most resources accumulates resources more quickly, and thus has the power to keep taking those resources. Sure, you can get rid of people who abuse this "too much", but the most powerful person will always be the one dancing on the edge and trying to push the amount they can take to greater heights. There is no being a good person under capitalism, there is only those who oppress and those who are "nice enough" to allow themselves to be oppressed.