Just because you're scared of the consequences of getting caught lying doesn't mean lying isn't a voluntary option. Voluntary doesn't mean free of consequences. You are free to voluntarily lie about your income to the IRS, you are not free from the consequences of doing so should you get caught in a big lie.
Tax reporting is voluntary. Taxes are not. I'm not nitpicking, I'm stating facts clearly.
You tried to make the point that people won't report their Bitcoin income to the IRS; you are wrong, people aren't going to suddenly all start committing tax fraud just because you would. Most people will stay within the law and report any significant income because that's what people do. Most people aren't political radicals looking to bring down the system and they don't care about your ideals. You are not representative of most people; you are a dissident.
What matters is that taxes are theft because in order to take that money away you have to threaten people with fines and jail. If you couldn't fine or put people in jail, my guess is that most would stop paying taxes. If you can't prove logically that taxes aren't theft, then, of course, it's okay to call people names and not argue like an adult, because that is all you're left with.