Historically technology has not eroded the middle class and has in fact increased it. The fear is that although that always held in the past, it wouldn't hold now because "AI is different." I'm not sure I agree - but it's psychologically clear that UBI would provide more "force" to stratify than just "technology" alone.
I'd like to push back on that.
Technological change can lead to loss of jobs.. And while I agree that there has been significant middle-class growth, creating the sizable middle class bell curve of the income distribution mentioned, I am not convinced it was primary caused by technological improvement. It can be argued that improved education is what caused that ( e.g. manual labors who picked up boxes and replaced by robot, can be trained to operate it), which is why we still see middle class bulge rising in the developing world but rather impotent in the advanced industrial economies like the USA.
I do not share the optimist view about AI being just yet another technology. It is a disruptive technology that affects everything and has potential to replace humans on scale that we haven't seen since the industrial revolution (not the third one). And we can't dismiss concerns that jobs will "be completely replaced by AI are in middle-class areas, such as professional services. Often, the practical solution is to find another job, but workers may not have the qualifications for high-level jobs and so must drop to lower level jobs. [
wikipidea]".
Also lets not forget that we live in globalized economy, where job can be easily outsourced (e.g. AI would create many low wage AI training jobs, but likely in the developing world), and the pressure of rising inequality (many people already struggle to secure stable, well-paying jobs with benefits) and the world economy shows signs of slowing growth and changing center of gravity. And I have no idea how these and other 3rd factors will affect things.
And the premise of the discussion that I'm (at least) having is "I still haven't seen a proposal that suggests how UBI can actually be sustainable without resulting in an even more massively stratified society between the people who actually work to have a "non-basic" lifestyle, and those who are just sitting there at the basic level."
Fair enough. I have no idea what that entails (will it be entirely unconditional guaranteed income?) it seem to me a question of income redistribution and one that would probably reduce incentives to work i.e. essentially what max said, why bother with a job if you can have a decent life without one.. that my 2 cents and I will withdraw from the pure UBI discussion.