The fully reusable SpaceX BFR will cost about $2 billion to 10 billion to develop.
SpaceX would need to have about 30 launches to reach $2 billion in revenue. Each Falcon Heavy launch or launches for NASA or the Air Force are higher value launches. Those launches are worth 2 or 3 times the value of a $65 million Falcon 9 launch.
SpaceX has two Falcon Heavy launches scheduled for 2019 and some NASA Dragon launches.