First of all, the top 20% make at least 80% of the money. (Example:Take everyone in a typical town of 10,000 and add Bill Gates to the town. The top 0.01 would be paying most of the taxes.)
The extremely wealthy make most of their money from investments (which are taxed at lower rate than salaries). CEOs of big companies get a lot of perks (use of corporate jet, chaffeured limo, etc.), stock options and bonuses. There is also a lot of their wealth that never even gets taxed like art work, jewelry and real estate that increase in value each year.
Now, without taxes, how do you pay for the roads that take everyone to work, or the schools, or military defense, etc.?
Okay, now here is why a National Sales tax is bad: There are tens of millions of families making less then $20,000 a year. (Minimum wage is 5.15/hour = $10,500/year). Taxing food, gas, clothes, newspapers, bus tokens, movies, etc. puts a disproportionate burden on the poor who need every dime to feed their kids and pay the rent. The Poor spend almost their entire incomes. The Rich sock it away and don't spend every dime they make.
So, with a 20% national sales tax, family making $24,000 spends $4,000 in sales tax on $20,000 in purchases.
A comfortable family making 240,000 (10 times as much) can live well spending 150,000 plus 30,000 in taxes and put 60,000 in the bank.
A rich family, making 2,400,000 spends an even smalller percentage of their income to live on, and pockets a greater percentage.
Don't forget, it's all those little guys making low or minimum wage that are creating the wealth for the corporations run by the big guys.
For the religious: isn't there some quote in the Bible about "each according to his means"?
The bottom line is that it costs a certain amount of money to run civilization and the poor may do most of the work, but they don't have enough money to pay for it.