I think the answer is that by the time AI can replace every function you do, it's also replaced everyone else and the world will either already have or will need to change radically.
I personally hope that the future becomes a UBI consumer-as-a-job thing, minus too much of the destructive impact that current consumerism has on the world.
Try to think logically. If AI eats all jobs, then nobody earns money any more to pay for everyone's UBI. The rich certainly won't do it.
Working together to make something is actually fun though. Seeing something you helped build be useful for others can be fulfilling. I'm not suggesting you should only live to work, but there are aspects of work that make life more enjoyable. I dread becoming a full-time consumer (aka retirement).