Actually, the reason iron is so cheap is because life chemistry and tectonic-hydrothermal processes have concentrated it. The bulk of the reserves date back from the Great Oxygenation event from 2-1 bn years ago when the first photosynthetic life oxidized the iron dissolved in the ocean and precipitated it at the bottom of the then-ocean. This didn't happen to aluminium, which is more abundant than iron, to the same extent. Aluminium was only discovered in the 19th century and only produced economically as a purified metal in the latter part of that century. Iron itself took some technology to become cheap and abundant and before the 12th century BC was regarded as a precious metal (see: <a href="https://en.wikipedia.org/wiki/Meteoric_iron" rel="nofollow">https://en.wikipedia.org/wiki/Meteoric_iron</a> ).<p>The price of metals does not match their abundance in the Earth's crust and least of which the Earth as a planet.
That's a rather tenuous connection. Nearly everything on Earth is due to the physics of dying stars. Once could also ask why so many houses in Greece are white and blue, and the answer would also be "because of the physics of dying stars."<p>This article focused on iron. The Earth's crust has more oxygen by mass than iron, but that point was left out.
Yeah, it's not actually the physics of dying stars, but the physics of the nucleus and the fact that iron is at the binding energy maximum [1].<p>[1] <a href="https://en.wikipedia.org/wiki/Nuclear_binding_energy#Nuclear_binding_energy_curve" rel="nofollow">https://en.wikipedia.org/wiki/Nuclear_binding_energy#Nuclear...</a>