Here in the USA, there's a lot of skepticism of the idea though... with the typical excuse being that people would just sit in front of the TV and eat bon-bons if they didn't "have to" work. I just don't see that.
I think in many countries larger groups of peeps think the same. That's why experiments are so much required. I don't have the figures in hand, but some experiments in my country showed that when a certain state benefit with obligations (like for instance 2 job applications a week) was turned into UBI, ie same benefits but without any obligations, the majority of people would still do something, from continuing trying to find a paid job, to starting unpaid jobs, like becoming a volunteer.
Something really interesting in my country: With about 17M people living inside the borders of the Netherlands, around 7M people do some to more volunteer work already. That's a super large amount of peeps in my opinion. All these peeps do some 'job' whilst not getting paid for it. This shows to me, that by far the majority of people are good.