While some people may find a 'basic' income sufficient many of them are already on government benefits anyway. The real issue with the current system is the effective marginal income tax causes people pay effective tax rates in the 80-120+% range stranding them in poverty. With basic income that does not happen you always keep most of what you earn so working more hours always useful.

EX: Someone on unemployment can get 340$ a week for 6 months and goes away if you have a job. Minimum wage is less than 8.50$ an hour so you could make less money working a 40 hour week than taking unemployment. Social Security has similar issues where someone on disability can't take a greater job a Walmart for extra income without losing far more money.