What's going on, HN?
(In general, whether people agree or disagree with an assertion I would hope they wouldn't downvote something as long as the person contributes enough to the discussion that the reader can understand what they are asserting and can check for themselves if the evidence they give supports or doesn't support the assertion.)
Wealth inequality in the US is so bad that the statement is true with pretty much any reasonable interpretation.
The top quantiles of the population (10%, 1%, 0.1%, billionaires) are paying less taxes than they should in a fair system; and that statement becomes increasingly illustrative of the situation the smaller and richer the quantile you choose is.
The fact that wealth inequality is _accellerating_ should be enough to tell you that the taxation system is unfair towards the poorer end.