What part of voluntarily giving up their wealth defies the definition of "voluntary?"

"all of these taxes are voluntary"

Is the place where the word in contention here. Just like if I point a gun at your hand and tell you that receiving the bullet is "voluntary" because you can always voluntarily cut off your hand.

That being said, I agree with the concept of taxes, but let's not kid ourselves and call them voluntary.

If you make the choice to interact with the US' economy you implicty agree to give the US a cut for its role in the creation and tending of that economy.

As a U.S. citizen, if I make the choice not to interact with the U.S. economy and move somewhere outside the U.S., I still have to give the government their cut. Only way out is to relinquish U.S. citizenship. No other developed country requires this.

So relinquish your citizenship.

Aside from the fact that there's a hefty fee for that, the US government will not let you relinquish citizenship solely for taxation reasons.

You could make up a reason, but that's stretching even your definition of "voluntary" under the law.