But won't each of those take up significantly more energy once they use Bitcoin than today? I.e the costs will be additive , and crypto aims to replace fiat. So crypto would need to be more efficient at the same scale as fiat to make sense.

Also aren't each of those used by significantly more people than Bitcoin? So the per capita use is less and they scale better?

Also how are you estimating cost of porn? Viewing cost? Generation cost?