because many would quickly find themselves not satisfied with having less than they see others with and there would be more than enough politicians lining up to

because many would quickly find themselves not satisfied with having less than they see others with and there would be more than enough politicians lining up to tell you how unfair it is to you furthering your discontent. UBI at levels needed to sustain your existence would not necessarily mean living alone how you choose to live but pretty much may end up in group homes or similar accommodations where many facilities are shared to make it affordable. Even then some areas of the world or even city will be inaccessible to many.