The problem with UBI is not that people would stop working, it's that the value of whatever amount is given as UBI will drop very quickly due to inflation.
UBI is basically the same as saying "everyone should earn above average".
This is why the Australian 1907 Harvester Decision didn't merely settle on an amount (42 shillings a week) but also included a needs based indexing (support a wife and three children, to feed, house, and clothe them).
UBI is basically the same as saying "everyone should earn above average".