> What's left for humans to do? Live on UBI, explore this wonderful world, colonize other planets..

If AI is so good then why would feeble humans travel to other planets? AI will use robots to discover them which don't need food, sleep, etc.

Humans on UBI will have a basic existence. UBI does not mean everyone will live in luxury, since luxury housing, locations are limited, so you'll get some simple aparment, simple food and bus tickets.

Evrything else will be luxury which those can get who can still be valuable in the system due to some unique skill.