[somenameforme]

I think "The Expanse" offers one of the most viable portrayals [1] of what a society under UBI would look like. One practical issue is that you'll end up with people who earn and create and those who passively consume, and that will lead almost immediately to a class system and segregation. And it's likely that basic criminality and other issues will come disproportionately from the consumption class, which will lead to calls from the production class for further regulations on their behaviors.

And in cases where the strain on resources is significant, you could easily see things like efforts to restrict the fertility of the consumption class which would enter into the domain of defacto eugenics. And from all of these sort of issues you're going to see a conflict arise between the two classes, but one holds all the power. It's not going to be pretty. FWIW, a decade ago I was a huge advocate for UBI, but my outlook on the realities of political leadership, and it's probable inescapability, has changed my opinion over time.

[1] - https://expanse.fandom.com/wiki/Basic_Assistance