A UBI will never work, the Soviets tried effectively that and it fails miserably.
You end up with the government deciding how much bread each person needs, how much the bread will cost, how much to pay a person so they can pay the defined price for the allocated amount of bread, etc.
Either utopian claims of an AI and robot-powered future are right and we don't need money because you can just have what you want, or money and resources will still be scarce and we will continue to compete amongst ourselves for resources.
You end up with the government deciding how much bread each person needs, how much the bread will cost, how much to pay a person so they can pay the defined price for the allocated amount of bread, etc.
Either utopian claims of an AI and robot-powered future are right and we don't need money because you can just have what you want, or money and resources will still be scarce and we will continue to compete amongst ourselves for resources.