Steel is very problematic. 90% comes from China. Proven reserves of iron will run out at some point and we'll need to find new ones. Smelting uses coal. Iron mining is environmentally destructive.
Amount in the crust is hardly relevant. After all there are trillions of tons of lithium etc. in the Earth's crust. Transition to a "hydrogen economy" would put unprecedented demand on existing sources. It's not realistic.
