You're asking how you opt out of taxes. You don't.

And everything you earn isn't rightfully yours. It's supported by an infrastructure of national defense, courts, police, building regulations, and so forth. You get many years of public school for free. Etc. etc. You didn't do this solo.

So the cost of all the benefits you get as a citizen is to contribute your rightful share, that share being decided democratically in which you have a vote.

Go to a country that don't have UBI? This seems like something that would easily resolve itself. Some countries will have UBI and some won't. If the UBI proponents are right and UBI leads to more human flourishing and a more productive populace, the UBI countries will win out. If the UBI doomers are right that UBI would lead to people getting lazy, the UBI countries will get eclipsed by non-UBI countries.

As impossible, as for me to opt out of your indirectly profiting from my contributions to the economy.

Society is a team effort. That’s what the elections are about.

> where I can keep everything I [rightfully] earned?

The same way any animal in the jungle keeps the food they earned.

Move to a place with no government and no services?

You haven't "rightfully" earned anything. That's such a loaded thing to say. None of your accomplishments are yours alone. We live in a society.

Return to fish.

When you pay the government to ensure that its citizens aren’t in desperate poverty you are also getting the service in return where you aren’t getting violently mugged and robbed all the time.

If every American was forced by some kind of mandatory conscription to spend a percentage of their life living in the poorest neighborhoods in America they’d probably become pro-social safety net pretty quick.