I think their current valuation isn't suggestive of a world that's going to change very much.
If investors were taking seriously the idea that this could be "it" with AI enabling even full automation — not superhuman AI, not even a fast learner, just AI that can fully automate everything we've currently got and not be limited to the subset of desk jobs that LLMs can do OK — it would allow the economy to double in size in whatever wall-clock time period it takes for the AI to gather enough training data by simply observing human workers doing the things the AI has not yet learned to do.
If self-driving cars are a good example in this regard, that observation time may quite large:
Current AI has not yet mastered full self-driving of cars in general conditions, despite all the cameras on cars gathering data about how all the other (human-driven) cars around them behave in real conditions. To take a somewhat arbitrary cut-off points for the sake of illustration, going from the 2007 DARPA Grand Challenge to today in self-driving cars, would suggest a growth of 3.9%/year.
Global GDP growth of 3.9%/year would be worth a much higher valuation than the AI companies are getting, and yet still be slow change.