What potential risks of UBI do you think the existing studies rule out?

I think pro UBI people often straw man anti UBI arguments as a disguised belief that Group X is lazy. I think pro UBI people do this because they are morally triggered by discriminatory work ethic beliefs (fair enough). I think that people who cite these studies might see the studies as ruling out the straw man, which makes them feel fuzzy self righteous feelings, but to me the studies do not even remotely address what I see as the actual risks of at scale UBI deployment.

It's simply: So far almost every experiment I've seen had positive outcomes in terms of employment, physical and mental health, overall happiness / stress reduction. That means we should keep expanding this until either we find actual problems to deal with or everyone is on UBI. We can spend ages trying to come up with various risks to rule out, but... what's the point in practice? We're basically agreed that we don't really 100% know how people will behave at scale. Worst case, we can discover and deal with real problems. Best case, it works great at scale as it does in small tests.

Unfortunately you can’t apply your Agile methodologies to UBI. I want to know about every possible tax edge case funding it because inevitably the upper class will find ways around paying for UBI. You don’t want it to become like Social Security where there is risk of insolvency in future generations.

The risks of UBI don't exist at the level of the individual. They exist at the system level. Studying individual level effects does not tell us anything about system level effects.