It sounds like you might be falling into hindsight bias, to be honest.

Stock traders building high speed data links are actually a perfect example of the limitations of private sector innovation. It was a $300 million project, they started seeing profits after one year when the project was completed, and they were able to calculate the speed increase well in advance and estimate how much more profitable their trades could be. So it was a short term project with very little risk and nowhere near the scale of government investment.

Mazzucato does talk about VCs in biotech and she thinks they have largely been harmful to innovation.