Yeah, but anything that ends up on the moon must have come from earth, so why not just launch from the earth?

> anything that ends up on the moon must have come from earth

For now.

The key multiplier to changing space exploration is making that no longer true. And you could do a lot worse than solid ground, with gravity, near Earth as a first permanent step.

That, and space elevators are feasible on the moon with todays technology which makes moving stuff into orbit much cheaper: https://en.wikipedia.org/wiki/Lunar_space_elevator

Using a lunar space elevator allows you to cheaply move materials from the moon into space and build huge interplanetary rockets without having to design your rocket around the rocket equation to get out of a gravity well.

In fact, the more I think about this, the more I think a lunar space elevator port is the key to exploring the solar system. You can build massive spaceships and refuel them without ever having to deal with the tyranny of the rocket equation.

You can send 50 rockets individually to the moon to deposit fuel and use it as a refueling/relaunching point. 50x fuel can't go up with the passenger-laden craft in the same way.

You can just refuel in Earth orbit though. That would use less fuel [1] than landing on the moon unless you were going to the moon anyway.

[1] https://en.m.wikipedia.org/wiki/Delta-v_budget

True but storage is an issue and as I said in another comment, Project Orion-type endeavors become more palatable when launched from a stable orbiting rock rather than empty space or a manmade platform.

Because of the rocket equation.

An even better launch platform is empty space (pick any Earth moon Lagrange point) where there is no delta V penalty.

There is increased complexity when launching from empty space / manmade built platforms. There's also the potential for Project Orion to be launched from the moon, where this would probably not be acceptable from empty space.

These orbits are unstable and require careful stationkeeping or a large orbital amplitude to maintain a semi-stable orbit.

L4 and L5?

But also no gravity which is problematic.