One of the things that distinguishes basic income from welfare is that the former is an unconditional transfer payment. That means that some of the folks who receive it don't actually need it. But it gains a lot of advantages over traditional welfare plans in the process - it is much simpler to administer, it doesn't require making politically fraught judgments of who is worthy, it eliminates disincentives to work that come from income cliffs, and it's easier to gather support since everybody sees a benefit.

Presumably those who don't need the basic income will end up funding a greater portion of it through higher taxes.