If money grows on trees, won't it's value go down?
If people get money for nothing, won't a large part of the population continue to do nothing?
What happens when you disagree with the administration who is currently giving you the UBI?
If you get what you put your attention on -- what happens when you reward non-production?
I believe production is the basis of morale -- if people don't feel useful, they'll degrade very quickly. Take away a man's right to work, and you break his spirit.
Educating people in things that have value, would yield much better results.
People are only what you allow them to be -- if you assume they're all incapable of producing, they won't disappoint. Get the government out of the way, and let new businesses come to life, and train people in those businesses, and you'll have a happy person, a happy business, and a happy society.
Giving a person some change on the street, encourages them to continue begging. Giving them a job, allows them to provide for themselves, and eventually, to provide for others.
That's my opinion.