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.