As is typical your assumption would be wrong. Replacing the Federal income tax with a consumption tax would burden those on the lower end of the economic ladder rather harshly. Estimates as to what % would be needed to replace the income tax vary considerably from a low of about 13% to 50% or more depending on what think tank is doing the calculating.
Looking at a legal product, like cigarettes, and using Florida as an example (because they have no income tax) it is estimated that about 14% of cigarettes consumed are smuggled into the state and sold illegally resulting in a loss of approximately $165 million in revenue.
Just so we are on the same page here, have you actually read any of the national sales tax proposals such as the fair tax? Were you aware that they usually have a "tax rebate" or other means of lessening the burden on the poors (under most circumstances they would receive more from the rebate than they would spend on taxable goods and services).
And okay, you used cigarettes as an example which has the same problem as weed, it has an excessive "sin" tax.
GOOGLE said:
In the United States, the federal tax on cigarettes is $1.01 per pack, while the average state tax is $1.93 per pack.
So, of your $6 pack of cigarettes, $3 is tax. That's 100%. I bet you there would be no black market for cigarettes if they were $3.60 (20% tax), the black market guys have to make a profit too.
But that's fine, I will continue to shop at harry teeters while you can do your shopping from the guy who lives in a van down by the river.