But it never became uneconomical to hunt elephants for their tusks. Poachers are now willing to risk being shot on site by government officials to get the ivory. They are willing to do this, because the price they can get for it is higher than ever before. And the price is still increasing, while there are now fewer elephants than when ivory was replaced with artificial substitutes. Extinction may no longer be imminent, but it is still a threat.
The price is high, but there are people willing to pay it.
Claiming that something will at some point be uneconomical assumes that there is a fixed amount that people are willing to pay for a product and that at a higher price people will prefer something cheaper.
