I don't think that's true. Human intelligence is limited, and our brains are inefficient machines.

The tools we built to replace muscles have mostly obsoleted raw strength for tasks like excavating earth.

There's no reason to think we can't do the same for brains. And then we'll never need to think for a living again. Some people may want to do it as a commercially insignificant hobby, of course, the way people lift and compete in strongman competitions today.

We'll have AI taking care of our needs, the way a good mother takes care of their children.