Why do centralised authorities have the right to tax decentralised currencies

The Internet is weird magical floaty stuff. So how can any centralised authority have any claim on our loot! I understand the need to prevent money laundering and all that good stuff. But if I choose to leave the current financial system and never on ramp back onto fiat and wait for the eventual larger adoption of crypto to come could that bypass these lil greedy poos from taxing me?