US oligarchy net worth

Is this true? Let's say the top 400 families average a few billion each. Then the average net worth for the bottom 50 million families would have to be about $20-30k. Seems possible.

Guardian: ... In fact, so staggeringly unbalanced has America become that the richest 400 American families have the same net worth as the bottom 50% of the nation.

If this outrages or saddens you, I recommend Who rules America?

If you believe this is a just, pareto optimal outcome, I suggest graduate school in economics, perhaps in Chicago ;-)