[panick21_]

Why would we launch from the moon to LEO, we are building sats (and humans) on the earth?

Assuming you mean getting materials from the moon, such as ice, the problems is that it would take 100s of billion in investment on the moon to do that practically. Everything from mining robots, transport and launch infrastructure. Plus infrastructure in LEO to refine that stuff.

If you do the math, assuming you have something like Starship, for those 100 billion to pay for itself, you likely would require an absolute absurd amount of materials from the moon. And on earth we have all the materials, refining capabilities and so on. Far, far cheaper to just launch it from earth in its final required form.

Unless you really want to build a fleet of inter-generational spaceship to explore the outersolar system, this is unlikely going to be make sense.

If you really, really want to transport stuff from the moon to LEO (for some reason), as long as it is basically ice, then its better to use some kind of mass accelerator.