1. Basic income + universal healthcare theoretically would be able to replace all other welfare programs, so there shouldn't be people "wasting" their basic income while drawing from existing programs. Also, I consider some level of frivolities as a basic need.
2. Many poor people stay on welfare instead of getting a job because there is a "gap" where if you get a job you actually are bringing in less income than on welfare. Basic income should remove this gap, which may potentially increase employment.
3. Most poor are not starving to death due to private help like churches and food banks in my experience. I know when I went through a small period of being below the poverty line we got a small amount of food stamps + wic and ended up needing help from those private entities too despite the fact that I had an above minimum wage job. However, cheap food is often bad for you food which is why a lot of them tend to be obese(food banks and the like often don't have the money to get very much good for you food). Combine this with a tendency to binge eat when you have food then have periods where you have no food to eat.