A legal trade in rhino horn is too risky
There are many precedents for successful, sustainable legal trading regimes that don’t threaten most wild populations of a species. Examples include deer farming for velvet (antlers) in New Zealand, wool harvesting from wild viçunas in South America, ostrich farming, crocodile farming and the most obvious analogy – sheep farming. Rhinos can be easily farmed, ranched and/or harvested in the wild and the resultant production could out-compete most of the supply from illegal poaching.
It is, in fact, most probably more risky to continue with a ban that has consistently failed for more than three decades, and which has no successful precedent.