So basically you're arguing there shouldn't be a resource overhang, because those resources should have already been applied while the AI was at a sub-human level?

I suppose one argument would be that there is a discrete jump in your ability to use those resources. Perhaps sub-human intelligences just can't read at all. Maybe the correct algorithm is so conceptually separate from the "lets throw lots of machine learning and hardware at it" approach that it doesn't work at all until it suddenly done. However, this argument simply pushes back the rhetorical buck - now we need to explain this discontinuity, and can't rely on the resource overhang.

Another argument would be that your human-level intelligence makes available to you much more resources than before, because it can earn money / steal them for you. However, this only seems applicable to a '9 men in a basement' type project, rather than a government funded Manhattan project.