Because the legacy of a great design for the masses (and once affordable to the masses) is appropriated, branded as a luxury item, and sold in small quantities for an exorbitant premium to the elite few. This video justifies that myth.
The Ant chair is really hard to find as a quality replica. I mean you might have seen it before, but a completely true-to-design Ant chair is very hard to find. None of my favorite furniture sites (Barcelona Designs and Manhattan Home Design) sells it.