Government investments are inherently more inefficient because the money is funneled through another layer, which bleeds off a portion.
And you somehow believe that private sector investments don't go through way too many layers and have bits filtered off at each layer? How cute.
Government investments are inherently immoral, because they use funds not acquired voluntarily.
Funny, I thought I voted for my government. Sure, the voting works far worse than it should (witness the folks trying to remove voting rights from voters who may vote "the wrong way" in so many states; also, gerrymandering), but overall it sounds pretty damn voluntary to me. And you always have a choice! Emigrate to someplace without an effective government (Somalia, maybe?) and test out your "everything is better without government" theories. Please.
You need both private and public funding or your economy falters.
I was involved with an institution which worked on (among other things) the Human Genome Project which was done with a LOT of public money. It was not something which would produce money in 2-5 years, so no private company would pay for it. But now, a decade later, many many biotech firms (both old big ones and small, nimble startups) are using that data to grow and make money, and thus pay taxes which could fund the next public research projects.
But since we're dropping most federal funding for research (because people like you complain about it and vote against it... Look! It's voluntary!) where will the next big economic surge come from? Not from the US at this rate, sadly.