Someone was telling me recently that all the cheap heroin influx into the country from Mexico was the result of drug cartels losing market to marijuana and needing to come up with a cheap competitor substitute. Not sure if that was accurate or not but sort of sounds intuitive in an economic sense.
I'm still surprised how marijuana posts are so frequently pushed in HN. My take is that the effect is negative, I've seen just a ton more brazen usage out in public once this thing hit with a bunch of phony Dr prescriptions given to perfectly healthy people. It's all a ruse in my book, you're either growing in virtue or backsliding. At best drug use is suboptimal for a thriving philo-generative culture to borrow Daniel Hannan's phrase.