A long time ago, people were born into social estates. Some were nobles and rich and some were peasants, villains or even, serfs.
Today, theoretically it's possible to earn as much money as you want. But in practice, it's much easier for some people and their children (i.e. medic, lawyer, pharmacists, entrepreneurs, notaries, bankers) to rise in social class and wealth.
The economic inequality may also be a source of injustice.
So, is modern wealth disparity really much different than noble priviledge?