Jonathan – I’m not so sure I buy that. You’re talking about “mean concentrations” and “shares” of the market, which might be a bit misleading because the market grew when prohibition was repealed. In a growing market a greater share of consumers might drink milder drinks while at the same time the total number of hard drinkers increases. Even alcoholics drink beer and wine in social settings if beer and wine is more socially acceptable. And, the repeal of prohibition widened the market to people who didn’t miss their occassional beer or glass of wine when they were outlawed but were willing to indulge a little when it became legal. So of course they won’t be buying rot gut just because it’s legal. The question I have is, Did the number of hard liquor drinkers go up in absolute terms? And I would guess yes.
Similarly, I have no doubt that if you legalized all drugs the “average drug user” would be an occassional pot smoker not a PCP hound. But the relevant question isn’t necessarily what the “mean drug user” looks like but whether the rising tide of drug-use lifts all boats. My main peeve with legalization folks is that they are so often unwilling to admit that repeal of prohibition will mean more, not less, drug use and addiction. I don’t think everyone who uses drugs becomes an addict. But an irreducible fraction of human beings do become drug addicts after trying them once or a few times. If you make the products safer, better, cheaper and more available you will increase the size of that irreducible fraction.