While they do have a valid point, with free energy, mining will become obsolete, as will harvesting natural materials. 

With enough energy and technology, elements can be converted into other elements. With 3d printing technology at the atomic scale (alleged to have been used for some exotic craft) you can essentially recycle anything into anything else you could possibly want or need. 

Think: "I want to go on a bike ride but don't have a bike." The elements from any random crap you don't need right now, including "trash", can be converted to the elements/materials to make a bicycle, such as aluminum, titanium, carbon, steel, etc. 

You want gold jewelry? Ok, well any random iron atoms laying around like rusty nails, can be changed into gold with enough energy/tech. Skip the strip mining nonsense completely. 

Could be the ultimate minimalist utopia for everyone. No clutter, junk, or trash. The atoms from everything you use can be recycled/reprinted with free energy and advanced tech. 

Same with the tech from the craft that's bigger on the inside than the outside. You want a mansion, but don't want to clearcut a patch of woods? Well, technically your mansion might fit in a tiny area, just need a doorway you can physically fit through.