[mmirate]

You're thinking solely about materials, and thusly forgetting about energy. (So did Star Trek, I reckon, but I degress.)

Humans require a timely supply energy to live and act. Converting energy into human-usable form, requires energy. Recycling and remanufacturing require energy just like mining and "unsustainable" manufacturing do. And even renewable sources can collectively provide only a finite amount of energy per unit time.