Not sure why people keep making this argument. If I'm obscenely rich and don't want to follow the rules, it's at least an order of magnitude cheaper and easier to have something on earth than mars. Buy a country or two, or set up a floating city in international waters. The challenges involved in each are peanuts compared to somewhere which has no breathable air.
If you're somewhere with no breathable air, and control the access to Oxygen, everyone else who was dumb enough to sign up to this trip is now under your complete control. That's what it's about.
It will always be infinitely amusing that Musk has gone from a walking-on-water Nerd Jesus to a mustache-twirling Bond Villain on this site in the course of a year.