If you have links to more detailed ressources on that topic, I'd be interested in reading them.
Once you have one human level AI you can make more replacing each human in the production of the human level AI - you basically start at the end point and working backwards replacing each job performed by a human with an AI. Once you get to the final job you will have a production system that can build AIs without any human labor. The system can make as many extra AI’s as wanted without any human labor - it is detached from the human labor market.
Unfortunately I don’t have any links discussing this. I think not too many people dwell on human level AI’s because the expectation is with AI’s if they can get to human level they will not stay at human level. Once you have AI’s that can make AI’s then they can make better AI’s until they far surpass human level. Understanding what these AI’s will be like is impossible for us.
Again, I don't see how that follows. Once you know how to build something, you can do it again. Of course. But what if building a functioning AI that can replace a human costs $100 bn?
Certainly it's not going to be economically viable to replace tasks that do not produce high ROI, even if you assume AIs are paired with indestructible robot bodies made out of unobtainium that are as versatile as the human body (have we even built one of those ever?).
I'm familiar with the idea that AIs could make better AIs and lead to some intelligence singularity, etc. Again, I think there's a lot of handwaving behind those ideas. We have no idea what the complexity of building more complex intelligence is, or what it even means.