Not necessarily.

First, the competition is international, and some is from governments who need a non-US supplier.

Second, the goal in most corporations isn't maximum profit per item but maximum profit per year, and if they can indeed deliver the prices Musk is speculating about of getting a million people to pay 100-200 thousand USD each to go to Mars, that allows the overall market to be much larger than if he can only charge 150 million (or even 1.5 billion) for 4-seat rides to a low orbit space station every six months.