Working to not die, isn't that the definition of survival? Or, as Rick Sanchez might say, grinding at your job is just surviving with extra steps.
> I really believe that most people will still want to be useful and make cool things people like
I really want to believe this, and it's true there are a lot of us that will do just that.
The issue is that there are a lot of traps and vices people can fall into. Alcoholism, drug use, even seemingly benign stuff like chasing digital approval are very ugly when taken to extremes. What snaps most people out of this stuff and keeps us in check is the fear of hitting rock bottom -- that is, you know that if you don't change you're likely going to lose everything / die / etc.
I've seen it in numerous lives, its only when they hit rock bottom that they decide something needs to change (that something being them). I know a former heroin user that destroyed every relationship in his life (including family) to get his hands on the stuff, and only changed when he decided that being homeless and waking up naked in a crack house was enough.
UBI takes away rock bottom. What's to stop a drug addict when there is no downside to staying high all the time?
As much as I would like to believe in UBI helping people, I would wager that there is a positive correlation between the people that UBI could help the most and people most susceptible to addiction. Maybe that's my pessimism leaking through, but I don't think UBI is a solution for them.
Again, I'm ALL for having better social safety nets etc. It's just hard to define what better is. You can meet a man's physical needs and still starve his soul.