I'm writing a speech, and it's about the topic "Private sector investment is preferable to public sector investment for Human Space Exploration"

I'm on the con side for this argument, and one of my reasons was that public sector will spur cooperation, while private sectors will just try and tear the competition down, and diffuse each others' ideas.
But I need to find some proof of this and I'm not sure how to go about it.

The private sector's goal is to make money. Does that goal serve the needs of the country?