It seems a little silly to put 71 years of private-and-public-sector infrastructure development alongside something highly targeted like the Manhattan Project. It might make more sense to compare the Manhattan Project to the first transcontinental railroad, as a similar targeted but enormously ambitious project amounting to a major technical milestone.

Likewise I don't think it makes sense to compare post-ChatGPT hyperscaler data center construction with all 19th-century US railroad construction. Why not include the already considerable infrastructure of pre-AI AWS/Azure? The relevant economic change isn't "AI," it's having oodles of fast compute available online and a market demanding more of it. OTOH comparing these data centers to the Manhattan Project is wrong in the opposite direction: we should really be comparing a specific headline-grabber like Stargate.

This categorization is just a confusing mishmash. The real conclusion to draw here is that we tend to spend more on long-term and broadly-defined things than we do on specific projects with specific deadlines. Indeed.