Simking, I challenge you to show me ONE Space Agency which is not over-spending. This is not because people don't learn, but mostly because when confronted with rigid safety and technology choices, time and money suffer.
I bet that commercial enterprises, when they go mainstream Space Exploration and be confronted with safety, technology, time and money and will have to haul humans, will have a tough life, or maybe realize that they are in the wrong business.
To be clear, commercial space is an inevitable and desirable thing, but it will, and should aim for objectives that have already reached by national and/or international gov agencies. I for one can see many opportunities for commercial LEO but would regard with suspicion any commercial endeavor of building a Moon base, or reach for Mars.
Commercial enterprises are even more susceptible than gov agencies to political, commercial, technological and corporate woes. A good example of what can happen to commercial entities has been given by the US car giants who have been momentarily saved by taxpayers' money.
So no, I don't buy the claim that commercializing Space Exploration will solve over spending while keeping safety, technology and national interests unhurt.
/Admin