Spacex expects they will receive additional funding from the U.S. government for the BFR and Raptor engine. Spacex would still build the BFR even without government money.
The US Air Force is supporting the Raptor engine development with about $74 million. The US government is spending $536 milliona on the AR1 replacement rocket for the Russian RD-180 engine. Ten billion has gone into Spacelaunch which has not launched after 7 years of funding.
The $406 million that helped support part of the costs for Falcon 9 and Dragon was money for the most productive and successful launch systems.
Spacex has more wealthy paying customers interested in the lunar orbiting mission.
The expectation is that when the BFR is developed it will be used to land missions on the moon and create permanent moon bases.