I've yet to meet an alcoholic that would do hard drugs. What percentage of hard drug users were former alcoholics vs. former pot smokers? I'm not saying that one leads to the other. But if one's personality leads them to some initial drug (alcohol or marijuana), then the statistics for that individual to progress to harder drugs should be the same. But I don't think that's the case.
And maybe that's the key. Maybe that's why people think that marijuana is a "gateway" drug. FWIW.
Ban booze---and tell kids it's as bad as heroin---and watch how quickly that ratio changes.
Probably because alcohol is legal. The type of person who would take a risk for a high is likely to take that same risk with any drug. It depends on what your "cost benefit" analysis of the situation is, and this is colored by many aspects including personality, temperment, family life, etc.
It's like an analogy I made earlier, dinner is not a "gateway" to dessert, but rather dessert just happens to come first. It's about the causal nature of the relationship. Does one lead to another, or does one just happen to come first.
There may be some good arguments against MJ, but "gateway drug" isn't one of them and only makes your side look silly.
IMHO, substance abusers tend to have a "drug of choice". The fallacy of your argument is that you're comparing "pot smokers" to "alcoholics". A valid comparison might be made between former alcoholics and former marijuana addicts, or between former social drinkers and former pot smokers. A "former addict" of any substance is much more likely to go back to their old habit than to take up a new one.