The Big Dig (Boston highway overhaul) cost $22bn in 2024 dollars. The Three Gorges dam cost $31bn. These are expensive infrastructure projects (including the infrastructure for data centers). It doesn't say anything about how important they are for society.

Comparing LLMs to the Manhattan Project based on budget alone is stupid and arrogant. The comparison only "makes itself" because Ethan Mollick is a childish and unscientific person.