World production is almost 20 million tonnes annually so that shouldnt be an issue. Its also not like electric cars use that much more copper than normal cars: normal cars have both a starter engine and an alternator plus all the engine wiring.

Also, electric motors can use aluminum wiring, and many induction motors have aluminum rotors since they can be cast at a lower temperature than copper.

So use aluminum, which has better conductivity per unit mass. And is essentially inexhaustible.

I wonder if we can "mine" all of the old copper wires (telephones, etc)?