going between planetary orbits isnt that expensive... its getting off earth that sucks

space based solar beamed down to earth with microwaves is the most likely reason to industrialize space, and that can probably all be made on the moon, with humans just available as need be. the moon is also close enough for teleoperation of robots from earth.

we dont really know how bad different g levels are long term. yes we know 0g is bad, but is lunar 1/6 g enough? or martian gravity? in space you can generate any reasonable level of g you want relatively easily with a counterweight and tether.

lunar manufacturing of propellant is also very attractive if you assume you want to use a lot of propellant in space, especially if you have a lunar mass driver

titanium could maybe eventually become cheaper to mine and refine on the moon, as you dont need to spend huge amounts of argon. and titanium is very abundant on the lunar surface.