As a sibling comment has said, there are scarcity of energy and resources. Now let's even pretend that can be a solved problem (not that I think it is possible,

As a sibling comment has said, there are scarcity of energy and resources. Now let's even pretend that can be a solved problem (not that I think it is possible, just from a physics POV): there will still be a transitional period where the issues I outlined will exist, and all of my arguments still apply during that period.