The skeptics of UBI say that if we just gave people the money they needed to live, it could collapse the whole system because most would just do nothing and it would be an immense burden on the governments.
My reply whenever I hear this 'argument' being trotted out is that it tells us more about the person making the argument than what the rest of us would do if we had a UBI. You've got to have a pretty shallow understanding of humanity to think that people would just lounge around all day.
That's why I mentioned Maslow's need hierarchy theory ;)