I'll add that as a retired person myself, I have found things to do with my time that seem (reasonably) useful. At the moment that includes writing a computer program, substitute teaching at the high school level, and occasionally writing a sci-fi novel. How much of that the average person could or would do if they had no employment in the post-scarcity world, I don't know---and for that matter, most (maybe all) of these would be replaced by AI. The point: what are people going to do to make their lives seem worthwhile? Which will add to the social upheaval and unrest you rightly predict.
I'll add that as a retired person myself, I have found things to do with my time that seem (reasonably) useful. At the moment that includes writing a computer program, substitute teaching at the high school level, and occasionally writing a sci-fi novel. How much of that the average person could or would do if they had no employment in the post-scarcity world, I don't know---and for that matter, most (maybe all) of these would be replaced by AI. The point: what are people going to do to make their lives seem worthwhile? Which will add to the social upheaval and unrest you rightly predict.