I'm interested in how making them illegal abates this? It seems like a non-sequitur to me. Further, even after making many natural drugs in categories that did this, we legalized tons of opioids made by US manufacturers, so that doesn't even follow with the actual law in the US.
Further, using alcohol regularly has a similar effect, and I'll bet you it's far more dangerous over time.
I will suggest instead that drugs are illegal for two reasons: Moralization, which is basically randomness applied to ethics; and because it allows our justice system to pick and choose who to imprison.