The space program research and development has yielded trillions of dollars in subsequent technological innovations. Governments have both the mandate and ability to drive such pure science frontier developments. Private capital would lack the motivation. Industry and commerce benefit from the trickle down of the resultant new technology. Another example of the state being a significant factor in the wealth of nations.

Crowdfunding. Millions of people would pay small amounts, just for the fun of it. Like zapping for going to the moon. But I guess that could end up in scamming people.