UBI is given to eveyone.  The people on welfare will receive them too.  I think it will help remove the stigma of welfare and I am sure it will also help a percentage of them to better their situation.

A low income person who works several jobs to support his family is not on welfare but can't retrain or quit his job to pursure something that may be potentially beneficial in the long run because he can't.  UBI relieves that pressure. 

Think of UBI as the bottom safety net.  If a person falls into a poverty trap, it is hard to climb out.  UBI relieves that.  

How many people you know can't re-train for better jobs or start businesses because they can't afford to have a non-income gap in between.