Re: “Good luck taking off from such a planet with your payload.”
I have a feeling that trying to mine or refine basic materials in space, or in near Earth orbit, will never be commercially viable.
Rare minerals and rare elements - maybe.
For use on earth, I agree.
For use in space, the materials have the huge advantage of already being there.
This particular planet would have enormous gravity, but iron would not be the prize. Heavier elements should also be present -- gold, uranium, platinum, etc.