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.
Boeing hasn't completely failed. Their ship actually worked just not with enough confidence to put people in it. That doesn't mean they're out of the game. There's still Blue Origin and also a bunch of smaller competitors working on different segments besides human transport. Astroforge seems ready to start mining asteroids and got up and running with shockingly little money due in no small part to the growing supply chain of components for commercial space travel.
Rocket Lab is growing into being a real competitor. They've been very innovative and successful in the small satellite market and, given what we've seen so far, I have confidence they will also succeed with Neutron which is their upcoming fully reusable medium-lift launcher aimed at supporting launch rates needed for megaconstellations. https://www.rocketlabusa.com/launch/neutron/
With the Starship the price to get a 100 ton object to orbit or one that is greater than 5 meters in diameter will suddenly become possible. Something previously cost infinity dollars will then be whatever price SpaceX charges. This is a decrease.
That's not true because your lack of a rolls Royce has forced you into buying a Kia, and not only suffering the cost of that vehicle, you are paying the lost utility and comfort of the rolls Royce.
Similarly, space operators who can't launch goldie-locks efficiency payloads are paying for multiple inefficient small loads instead.
This is a very strange way to think. You could apply it to anything that could not exist in the past that people happily pay for today. "Medical care was much more affordable in middle ages!"
Despite their slow pace, it's quite clear Bezos and Blue Origin + ULA will continue to plod forward. They're real competition with plenty of money behind them.
Tesla is another company that had a near monopoly in their market space for a couple of years, but that didn't stop competition from showing up. It is notable how their margins have dropped as competition heated up however.
