massive universal sales tax like that would absolutely bone the low income people to death and totally let the rich off the hook.
It might actually collect more from "the rich," depending upon how much they consume and how much they currently pay in income tax. Some of "the rich" don't have significant income taxed at normal rates. I believe Obama has bitched about this, about a million times or so.
And as for screwing the poor, the fairtax incorporates a rebate system that refunds sales tax paid up to a certain "poverty level" line.