Doing what exactly? What industry could Mars possibly support profitably?
Government crew and supply launch contracts probably, though these don't need to be "profitable" in the conventional sense for the entity footing the bill.
All that's needed to be profitable for the launch provider is to convince Congress that it's in America's interest to establish a public-private project for a moon base and a Mars base. Now more than ever, when framed against a background of an ascendant Chinese Space program that will soon be sole operator of a space station.
Once the "Race to Mars" is won, NASA can grow soy-beans, do bone density studies, and any other science shit the NASA nerds can come up with post-hoc, but the main point will just be being there, and having the Stars and Stripes on the first flagpole planted in Martian soil.
I can see plenty of people going to Mars — religious groups, cults, anyone who wants to explore the final frontier, the most extreme preppers (which Musk arguably is given his "multi-planetary" arguments), and anyone who would like to build their own mountain-sized space castle.
What I can't figure out what any of those people might sell to Earth such that people on Earth are willing to trade for it, except for information which people on Earth can also produce without paying so much for a ticket.
(if you haven't played Bioshock this probably wont make much sense - but if you have and listened to all the audiologs, i'm sure you'll find a bunch of parallels)
He obviously has plans to do neither of those. What makes me question why does he even want to go there... But a magnetosphere strikes me as "earlier infrastructure", while terraforming is "is that even possible?"
SpinLaunch on the moon wouldn't even need the vacuum chamber they use on Earth, but it would still need that on Mars.
The biggest down-side of the moon is the long night, but the solution to that is the same as one possible solution to the lack of magnetosphere on Mars: a very, *very* thick wire.
(I've not done precise calculations for this, but I have considered the scale needed for "thick wire" on an Earth-scale global power grid, and for that I was getting Earth's magnetic field at a distance of 11 km from a 1.36e6 A current, which in turn meant I had a 1m^2 cross section; naturally this is only going to happen if you have some serious automation for processing lunar/martian regolith into aluminium).
Definitely, and by a large margin.
If I said Mars combines the warmth of Antarctica with the moisture of the Sahara, the air pressure of the peak of Mount Everest, the environmental quality of a superfund cleanup site, the surface illumination after the 1883 Krakatoa explosion and subsequent volcanic winter, and the UV radiation from a completely destroyed ozone layer…
…if I said all that, I'd be understating how harsh Mars is.
The most positive thing I can say about colonising Mars is that the mere ability to actually do so will mean being able to recover from any possible catastrophe that comes our way.