You are remarkably under informed about the many developments that space R&D has given us. Half the diagnostic equipment in a modern hospital has its roots in Aerospace Medical Research. If you can keep a man alive on the moon you can keep him alive in a lot of situations. The benefit of going to Mars is not what we find there. It is the development of the technological means to GET there. From a purely economic stand point it makes more sense to go to and asteroid and mine it. There have been studies that show that could easily pay for itself...
You have to stop and use your head about where all that money goes. We don’t just pile it up into a stair way to heaven. They PAY that money to tens of thousands of engineers, technicians, and scientists to build new and amazing things. The money does not vanish, it goes right back into the economy as those people spend their pay. Also, preeminence is space does the same thing as a strong military. Who will attack us when they know we are over their heads all the time, even in unarmed spacecraft. Intimidation pays off. Who will take the US seriously when Chinese and Indians are walking around on Mars and we are just spending more and more on the welfare class?
Of course I for one prefer anything that IS worth doing in space is worth doing via private funding. But that does not mean there is no useful government reason to invest in space.
I can see you've fully drunk the NASA Koolaid. You have a remarkable lack of understanding of what really goes on in R&D if you think that we wouldn't have those innovations without the space program. I refer you to Bastiat's That which is seen and that which is not seen As a starting place to open your eyes to the wastefulness of GOVERNMENT sponsored research.