"Given that ChatGPT and other forms of generative AI create their output by synthesizing what they find on the internet"
Wow that is almost, but not completely, the opposite of what it does. And given its current form, it cannot really replace much (and we don't really know how it will look in the future, or if it will be much better than how it is now).
Looking at self driving cars, how much money was thrown at the problem, and how far are we still from looking at a fully self driving car, I would say AI replacing jobs is 90% marketing and 10% substance (there are fields where it is becoming very effective, like for example machine translation).