There's a economic basis for government investment in roads and our common defense to name two primary areas of investment. It's more efficient for the government to provide these than for private individuals or groups of private individuals to provide them. That's not to say that there hasn't been a lot of waste or that pubic monies haven't been directed to friends, insiders or supporters along the way for reasons other than pure economics. Even during the American Civil War, there were instances of people selling rotted meat, etc. to the military which resulted in some of the federal statutes now on the books.
It would be interesting if it turns out that we've been chasing the wrong energy rabbit attempting to convert solar energy into electricity if it turns out that some spectrum of energy is directly useable and more efficient than converting solar energy into electricity.