In my mind, the cause of this sort of conglomeration is that our society is an exponential meritocracy rather than a linear one. In that the more merit (money, power, points, karma etc.) you accumulate, your ability to accumulate even more merit rises, resulting in a stratification of society that starts out slow but rapidly accelerates after a while.

Best expressed as: "To turn 100 dollars into 110 is work. To turn 100 million into 110 million is inevitable." -- Edgar Bronfman, Sr.