When I was in the military reserves, there were some guys who graduated High School and went straight into a minimum-wage job, working at Home Depot and the like. At first they thought it was great -- I have
my own place! Sure, it's a room in a flat shared with three other guys, but it's
mine! I have
my own car! Sure, it's an old beater that guzzles gasoline, but it's
mine! I can buy a Playstation and afford whatever game I want, and stay up as late as I want!
But pretty soon, once the novelty wears of, it begins to pale. I mean, I have my own place, sure, but it's with three other guys; not someplace I'd want my GF to move into, and definitely not a place to raise a kid. I have my own car, but it's a piece of junk. I can't really afford to go to concerts or long trips, all I can really afford to do is sit around at home and play games on my PS/2.
So, after 2-3 years they all started do things to make themselves more valuable to society: one took classes to become an EMT. Another took classes to become a fire fighter. They landed better, more stable jobs, and could afford to move into a nicer home, get better cars, attend concerts and sporting events, go on trips, start families.
That would be my ideal for how UBI would work: make sure people never have to chose between a bad job and starving or being on the street; but also make sure they have a clear path and opportunities to improve their situation and become more valuable to society.
Are there "deadbeats" who would just play video games for life? Sure, but there already are. I'm not sure how much those kinds of people contribute to society, even if they are working a minimum wage job to support their lifestyle.