I was thinking about this a while ago too. It seems like there will still be poverty and large disparities in wealth, even if we were to have a fully automated economy that produces everything that we need with very little effort. There will still be an elite who have all of the high tech weaponry/make the laws and are able to have a monopoly on these fully automated industries.
That means there is a systematic problem, we'd better find where the problem is
I think the purpose of making AI and robots is to free human from reputational labor, thus gain more time to enjoy life and create new things, so even if 90% of people do not have a job, they might have some more meaningful things to do