That's what people do, but to do so they need to work in growth industries and geographies. Otherwise you don't make enough to do just that. Thus they go somewh

That's what people do, but to do so they need to work in growth industries and geographies. Otherwise you don't make enough to do just that. Thus they go somewhere that does, in this case Tokyo mostly. Which makes the situation worse for the prefectures that they leave causing brain drain, and now those that stayed need to have the taxation to cover for the two they were already on the hook for, and now the two that the person gone to individualistically "save for their own retirement". This generally leads to services and infrastructure getting shut down. Not more stuff spread out to less people because certain modern lifestyle features, things like hospitals, need a minimum level of patients and experts to function well above zero.