[SinParadise]

> We very rarely need specific minerals.

Because historically we do not have technology complex enough to need specific minerals. Now we do.

> Most of these needs we can fulfill with many different minerals. And the amount of all [1] minerals in earths crust is staggering compared to any foreseeable futre, so we are just going to flip to whatever is easiest/cheapest to dig.

There is another factor at play though: energy required to extract the minerals. Ones deeper in the earth's crust are likely more energy intensive to extract and perhaps even purify. At some point it won't be worth it.