Conversely this is why space mining is kind of a big deal. If we could get large quantities of pretty much anything that works as a propellant without launch costs, that would change a lot of things.
Even aluminum mined on the moon would be potentially useful.
And due to the oddities of space travel, it costs a lot less delta-v to go from the Moon to Earth orbit than it does from Earth to Earth orbit, especially if you do aerobraking.
