1. SpaceX will never have a monopoly over launch because it's competing with lots of governments who will never give up their rocket programs. ArianeGroup, Japan/Mitsubishi, Russia, China, and India all have active launch programs (although Russia and China are isolated right now).
2. There are a truly stupid number of startups trying to compete for a slice of the launch pie. Most of them are in the small-lift launch segment for some reason, even though it's probably impossible to run a profitable rocket launch business in that segment of the market. But there are enough companies that aspire to launch larger rockets that SpaceX needs to be on its toes.
Blue Origin, Rocket Lab, and Relativity are probably the main future competitors to SpaceX. And both Rocket Lab and Relativity have talked up prices that are equal to or lower than what SpaceX is currently offering.
3. The DoD and NASA are actively working to prevent SpaceX from forming a monopoly in the US market.
These companies will lose billions for years with this single intention.
The true cost minus the listed price adjusted for years of interest and extremely high VCreturns are all useful numbers to know because that adjusted by a risk multiple will tell you how much wealth the investors are expecting the monopolization to transfer from the taxpayer to their pockets.