I remember learning about sea floor nodules back around 1975.
Over the decades I have heard the same statement in more or less the same words, they are too expensive to collect and process until the price of Copper or Manganese or one of the other metals they are made of hits a certain sustained price point.
When it comes to Copper specifically, the only reason it is still so popular for things like wiring is its relative low cost. You can make household wire out of aluminum, except people are scared because of the rash of poorly installed aluminum branch wiring caused house fires in the late 1970's. Heck if you are willing to use thicker wiring you can cheaply make circuits with steel or better yet iron wire.
Back during World War II because of the need for copper for war material lead the government to use silver wiring for the Manhattan project. Don't bother scavenging for it, as soon as the war ended they ripped out all the silver wiring and replaced it with standard copper
We have predominantly used copper for the last century because it was convenient and cheap. Make it inconvenient and expensive and that will change. One of two things will happen, new sources will be developed making it cheaper, or substitutes will be implemented. If our civilization crashes it won't be from a shortage of electrical wiring.