Ideally you would use it for building up space infrastructure primarily. You might still ship some finished products back to Earth, that would be much more mass

Ideally you would use it for building up space infrastructure primarily. You might still ship some finished products back to Earth, that would be much more mass efficient. BTW, once you can have your payload trajectory intersect with Earth, you will get braking for free thanks to the atmosphere, effectively shaving half of the needed delta-v. Same thing on Mars.