I'm not sure what definition of UBI you're using, but not all forms of UBI need to cover the entirety of living expenses. UBI is just having income without strings attached. This very study is showing that even small amounts of money can help people get out of shitty situations.

Also as someone who lives in Dever, it's not that expensive. Sure $1500+ is what you'll pay around LoDo, but there are plenty of cheaper places.