The joke of it is, what percentage of the ignorant, superstitious buyers who pay for "rhino horn" actually receive a product containing any rhino horn whatsoever? I would bet very few.
When there are no rhinos left at all, people will still continue selling "rhino horn" unabated, and the gullible will continue to part with their money for it.
Its a bit like wood from "the true cross", of which reputedly there was more than enough to build the Spanish Armada. Too many people are too gullible and, like Barnum, there always were and always will be chancers willing to part fools from their money.
From the poachers' perspective, if I eked out a subsistence living for myself and my family, but could earn a small fortune from killing one animal, then I can understand how some might be prepared to risk their life (which they do, as armed guards patrol most of the main areas) to make a killing, in both senses of the word. It is too easy to try to attach sentimental western values from people who have it comparatively easy, to people who may be desperate. It is wicked, but I am not so naive as to say if I were in their shoes, not mine, that I might not be tempted. Can you?