At the end all of this boils down to economics, and instead of spending trillions to terafform Mars, you can buy large swathes of unproductive land on Earth and try to develop that...
Why climb a mountain?
No it was an investment. Military and civil research (in so many fields), as well as propaganda (to USSR, US and the world). It was the cold war.
See also: https://en.wikipedia.org/wiki/National_Aeronautics_and_Space...
> Why climb a mountain?
Sports, hobby, in some cases I am sure also inferiority complex.
Neither were done by companies though, so the question still holds, when there appear to be more viable options.
I am not going to judge what makes economic sense, but these questions really don't seem related.
That said I think I'd prefer they kept it more as national park / site of special scientific interest rather than a construction site.