This short-term thinking makes me pessimistic about UBI. Everyone's addicted to work despite automation and AI creating less need for work. And thinking we live in a zero-sum game where if someone else is benefiting, it must be hurting them somehow so they must block it. If someone's getting a "handout", they're a lazy bum.
Why would you have to work harder when employers of jobs no one wants to do (for a given wage) have to either increase wages or embrace automation research and development (thereby likely speeding up its systemic adoption and reducing the necessity for manual work even more)?
Where developing countries have vendors on the streets, industrialized nations have vending machines instead, by pure economic and demographic necessity. The existence of an automation tool doesn't imply a human having to work harder somewhere else.
And why do you assume people would sit around doing nothing? I don't think that's a natural thing for most people to do.
How financial and social systems are set up seems to be very much a societal choice, unless it goes against some physical, basic economic or global trade limitation.