Are you talking about the idea that taxes are theft, (which I didn't disagree with more) or the idea that wage labor is theft because your employer sells the products for more than they pay you to produce them (which is absolutely theft, imo)?
There's a baseline level of consumption required to survive. Meaning everyone eats, rents, drives to work, buys an entertainment system. Paying for what you consume is a regressive way of generating tax revenue as the tax is raised from the poor masses.
Progressive taxation exists because people with more income have more disposable income. When you tax a poor working single mother of three and she must choose between buying food or paying tax, you will get riots eventually. When you tax a millionaire who's choice is buying a sports car or paying tax, riots don't usually happen.