Technology has always managed to eliminate traditional jobs in the past... such as farm jobs... and factory jobs... surely more jobs to follow.
However, humanity has always managed to create jobs in new fields. Do you think back when most labor force were farmers ever dreamed of computer related jobs?
I still believe solution to narrow the gap between the rich and poor isn't to just give money away to the poor.
People need to learn to how to make a living and learn how to manage their own resources.
I do believe some sort of UBI may perhaps be inevitable..., however, there must be more than UBI for our society to function healthily.
Imagine in the Star Trek universe... do you think there are folks on board the Enterprise just sitting around in the holodeck enjoying themselves and collect their UBI and do absolutely nothing because everything is automated? Will Capt. Picard allow this kind of behavior to continue unimpeded on his ship? I don't think so.
So in the future, when we no longer have poverty in our society, perhaps we'll no longer be earning money, but earning respect or some other sort of performance metric... Surely not everyone will be Captain Picard, but you can't remain a Lt. Barkley forever. We need to figure out other ways to unlock people's unique potentials.
To simply assume that some folks will be totally useless when we have automation is underestimating human ingenuity. We can throw money to solve problems, but we'll never solve problems just by throwing money at people.