The major problem I see is the underlying assumptions that
1) The results of these projects would never have been done in the market
2) The projects were completed in the best possible way and with the best possible results
3) The results of these projects was/is the best past, present and future use of the resources they have and do consume
Sure, there have been government projects especially through the high risk/reward program DARPA, the internet for instance. But you will notice that the Internet was “invented” in the 50s or 60s, but never really came into wide use until the the market really made use of it and demanded its services decades later in the 90s.
Government spending, especially things like research are a prime example of Bastiat’s “That Which is Seen and That Which is Not Seen” and Hazlitt’s One lesson of economics.