Every time I read somebody describing their experience with something I wonder if the reduced drug usage is one of the lead causes of the lack of warmongering we got since the late 20th century.
Reduced? Alcohol consumption is down (depending on how you view the stats), but drugs are winning the War on Drugs. Everyone else is losing. Legally, oxycontin is more highly regulated today, but the opoid epidemic is, well, an epidemic. Cannabis is legal for recreational use in many states. I willing to buy that something that's widely available in today's society has lead to less war (Internet porn, perhaps?), but I'd be surprised to hear in what ways drug use is down.
Drugs used to have institutional usage. They used to be distributed by armies, take part on religious practices, have explicitly regulated import quotas to keep the population "calm".