If you believe that a band of thugs extracting what they want from you at gunpoint under color of law is in any way legitimate, what the hell difference is it if they do it based upon income or based upon current net holdings? From an ethical standpoint, it is the exact same thing.
Band of thugs and government is not the same thing. You seem to be ascribing government as if it were a "band of thugs" and then attempting to be technically correct because you are saying that the "band of thugs" is acting under "color of law."
Your framing amounts to faulty logic, even though anti-government folks like to talk like that, if you are mixing up the difference between government and thugs (or at least presuming government to be "thugs").
'Splain me the difference?
If something is unethical for one person to do to another, then that thing is unethical for any group (e.g., so-called 'government') to do to any individual. For if the government gets its authority by assent of the governed, that government has no legitimate power that those governed do not have to begin with.