That particular statistic is useless without further context, and thus is a favorite of Fox News and other right wing ideologues. If 80% of earners earn one dollar a year then obviously it's low. If 80% of earners earn 1% less than the other 20% then it isn't.

A better statistic is to actually look at the tax rate paid by the top earners compared to lower earners. Top marginal rates on employment income including state tax is often over 50%, which is probably plenty.