"Unfortunately, there is an ignorant hoard out there that falls for this cynical pretense. "
Indeed there are ... but you seem not to realize who they are. As for "the flaw" (as you put it), one has to presume that means that should the income tax laws be changed to tax such accumulated and already-taxed savings that the government would somehow "owe you" and some financial adjustment should be paid. I don't think so. You pays your money and you takes your chances under any tax system, but especially an income based tax system, that the tax laws will NOT be changed so that you can benefit in the future. Yet if you look back you will see that is a fool's game. Income tax laws have frequently been changed in the past - seldom to the benefit of the taxpayer - and will no doubt be changed again in the future should income taxes remain.
To believe that because you have lived and earned under a given tax system and prospered to some degree does not mean that the government "owes you" by refunding all of the taxes you previously paid since, after all you were only following the tax laws and making your choices re taxable vs. nontaxable savings. The tax money you paid was spent by the government on pencils, paper, and pilotless drones as well as many other things. Do you think that these government expenditures (that you, Mr. Taxpayer, have allowed I might add) might somehow be retrieved by the government??? I think not - those tax monies are gone; spent. Why should the government now "owe you" for following the law and now, in effect, double pay for the tax revenue you provided under that law???
The answer is, of course, they not only shouldn't but they won't. Under the FairTax, though, you would have a much better shot at getting back what YOU THINK the government "owes you" since income is not taxed. The fact you choose to blow your funds on a executive boat, a land cruiser, or other expenditure is, however, your choice - and neither the government (not the other taxpayers who provide its tax revenues) owe you a single red cent.
I believe that I have the right to argue and collect supporters who would oppose the unscrupulous "FairTax" scheme. I believe that showing the group of voters who would be screwed by this scheme that they would be loosers should something like this be enacted, that by numbers, as well as principle, will succeed in defeating this crooked scheme as it is presented, Pigdog.