> Why is it some shock-horror thing that people worked less?
Because significant portion of UPI proponents argue that it will promote working more and higher productivity. The typical argument is that it will remove barriers that prevent better worker-job matching.
A significant proportion that is not the majority? I think the vibe about UBI was always "people will work less and employers will have stricter competition when hiring employees".
hard to say either way without statistics on actual UBI proponents. I would argue most, but my opinion is also based on cumulative vibes from vocal proponents like Andrew Yang and random internet commenters.