Human eggs are about the largest single cell humans produce, about 0.1mm in diameter.
But human eggs don't provide nutrients to the fetus, they grow the placenta to do that. So over all the entire process would have to change to something probably impossible. Consider the ostrich lays the largest egg now, and ostriches are larger than humans. Humans that would need a far larger egg.
The math just doesn't work for humans to have a hard shell egg.
Ok, try aluminum. Used to be super rare, rarely used. Now you can't throw a cat without hitting some. Production efficiency went through the roof, price dropped like a rock, and suddenly there's aluminum things everywhere. Efficiency created far greater demand due to the drop in cost. Energy is even more useful than aluminum, it literally makes aluminum. And yet, we're using less, as we get more efficient at making it.