I have to disagree with Kmitch, Without the initial Govt investment in the Space program for national defense purposes, ( it was after all a spin off of the ballistic missile research and the Air Force's never ending desire to go higher and faster ) there never would have been a space program .
Had there not been a European desire for the natural resources of the America's, (including open land to resettle some of their excess population )colonization and settlement of the America's would have taken far longer, possibly centuries.
Since the 40's or 50's Science Fiction writers, (many, such as Asimov, and Benford , being serious scientists in their day jobs ) have been theorizing on the exploitation of space as a future source of many raw materials, particularly metals .
They have also been thinking about ways to lower the per pound cost of launches. Before many of the needed technologies did not exist, some of the technologies we needed to invent the technologies we needed did not exist, (such as computers, man made materials and reliable wireless communications ).
Look at Virgin, or Rutan's Space Ship One. If you can convince industry that they can substantially increase profits, whether through tourism, or mining or whatever. They WILL find a way to do it.
It would not surprise me if the first colony on Mars were financed by Bally's of Lunar.
It seems that none of us are opposed to the idea, we're just debating where the financing should come from.