As much as I agree in every respect with the first paragraph of @Haleth‘s response, the second one is actually incorrect.
For this reason: If we had a cheaper and more efficient way to get into space, then the economics of life on this planet would preclude the need for whatever minerals are likely to be found on a rock in space.
To demonstrate this, consider fresh water. This is arguably “the most valuable mineral” on Earth. (No, it’s not a rock, but it’s a chemical compound, same as any other mineral.) It’s the most valuable mineral because life itself depends upon it. In some parts of the world we can take the presence of potable fresh water pretty much for granted most of the time. (At times of service interruption and natural disaster we often find how much we take “fresh water any time we want it” for granted, and how foolish we are to do that.) But there are some places on the planet where the absence of fresh water makes life impossible for anyone but a temporary visitor or one in transit between livable places. If we had “energy cheap enough for space launches at nominal cost”, then we would also have the cheap energy to create desalinization plants and pumping stations to put fresh water anywhere we wanted it on Earth. So why go to space, in that case, to mine frozen or liquid water (assuming it could be found) to bring it back to Earth?