This is spoken like one who knows nothing of science. Back in the day, there was quite a bit that was discovered through private lab and individual. And to this day, some of that remains true. But the time scales and financial scales are far too large now for base scientific research and that is what is needed for the further advancement of science. Private companies take what is discovered in government labs and academia and then develop that into something economical and with commercial value, but they can no longer do the base. Too much money, too long of a time to be profitable. Scientific advancement cannot halt just because private business ran its course and can no longer be relied upon to advance it.
Sending probes into space does matter, it lets us know about our solar system and universe and help us to understand some of the laws of nature, the very laws that can lead to break throughs that can latter be developed by private enterprise. Furthermore, we need to. The entire history of mankind has been that of scientific advancement and understanding, it's what our species does. Well that, and destroy, and who knows what sorts of weapons you can eventually create if we just know the right things. If you're so interested in killing over creating (I'm not).
NASA has brought us grand understanding and huge advacements in technology, academia and government research has laid the bedrock upon which private enterprise can research and refine technologies that are ultimately brought to the consumer. But the base is too expensive for it to be done alone. Do you think that private business would have invested in Bose-Einstein Condensation? Neutrino oscillations? Particle physics? Gravitation waves and lensing? Optical combs? Laser Cooling and Trapping?
No..they do not have the time, they do not have the money, they would not know until much further than after the fact if something could even be profitable. They are driven by profit and profit alone. It's not a bad thing, we need that dynamic too (which is why we have both government and private enterprise), but it brings with it limitations. And one of those limitations is that private business can no longer perform the base research necessary to advance science and technology.
So yes, private individuals laid the basis for powered flight, but they didn't create lasers, they didn't discover the Higgs, they didn't discover atomic clocks or even GPS, they didn't discover relativity or radioactivity, etc.
Time scales, financial scales. These must be considered if you wish to have private business handle something, and for base research and scientific progress, they do not have the means.