To go to Mars, SpaceX needs lots of steady revenue and low-cost launches. The more launches SpaceX does, the lower the cost per launch, due to the manufacturing

To go to Mars, SpaceX needs lots of steady revenue and low-cost launches. The more launches SpaceX does, the lower the cost per launch, due to the manufacturing learning curve and high reusability. Rather than wait for customers to come up with applications that require lots of launches, they made their own.