Implementing UBI doesn't mean everyone gets money. Those with jobs, for example, or those with millions in the bank, won't. But you likely know this already.
If it doesn't go to everyone, it fails the first descriptor "Universal".
Never mind cutting off "those with jobs" would introduce all sorts of problems like we see with similar "benefit cliffs" for just basic welfare systems.
Part of the promise of UBI is lower administrative costs and reduced political pork. Adding in conditions like the ones you propose would be expensive and arbitrary.
In Brazil, many benefits occurs like that by age, gender, low-income or other discriminatory rule and multiple times to drive this group to vote into specific parties, perpetuating the low-income and maintain as maneuver mass or a ventriloquist dummy.
Never mind cutting off "those with jobs" would introduce all sorts of problems like we see with similar "benefit cliffs" for just basic welfare systems.