When it comes to UBI, there's an interesting psychological phenomenon.
I believe that McDonald's and similar establishments could have automated away the vast majority of their work force years, maybe even decades ago. And yet there are still people working there. In fact, McDonald's is often viewed as many people's first entrance into the work force, and as a safety blanket if anything goes south (well worst case at least I can go work at McDonald's or something).
In other words, I believe McDonald's and its kin are a form of social welfare.
We see this elsewhere, in less subtle ways. Tons of jobs that shouldn't exist, but which are kept afloat by regulation designed specifically to preserve those jobs.
We pay either higher taxes or higher pries to achieve both of these forms of social welfare.
And yet, support for these jobs and social actions is generally quite strong. Hence why restaurants haven't fully automated themselves; the market would vomit at the idea of those thousands of jobs being replaced by machines. Regardless of whether that would save people an incredible amount of money, they are willing to accept those sacrifices in exchange for those jobs being available.
In that light, what's the difference between what we have today versus UBI? Either you're paying someone to do functionally meaningless work, or you're paying them to do "nothing". Under the former, their work is _truly_ meaningless. Under the latter they at least have the chance to do something beneficial for either themselves or others.
Personally I haven't formed a real opinion of UBI. Even in light of the above arguments, the complexities make it a problem not so easily reasoned through. But I suppose my point is that UBI isn't as drastic a step as many imagine it to be. It would be more of an evolution of our existing, de-facto social welfare programs.
EDIT: Addendum: When I use the term meaningless here I'm really just using it for the sake of argument. Obviously no one's work is meaningless. Just because a machine could do the exact same job that a human can do, doesn't mean that the task, as performed by a human, is meaningless. The true thrust of my argument is that a human performing the task subtracts value from the economy relative to a machine doing the job. It's sub-optimal.