In my opinion, all the stuff about "gateway drugs" is bullshit. they always give statistics about how 99% of meth users started with alcohol, cigarettes, or marijuana, but I'm willing to bet that the percentage of people who start with one of those three and go on to the harder stuff is infinitesimally small.
Also, way I see it, my the time most kids are in high school they've probably made up their mind of whether they'll ever do drugs or not, and any further propaganda attempts to sway them are going to be ineffectual. By ninth grade, the schools had already taught us all about drugs, and there was no more new information to be given. Also, most of the propaganda fails by trying too hard to seem cool to the young demographic, when you can tell it was made by a group of overprotective aging parents from the suburbs, the sort of trying to be cool that tends to drive kids off rather than get them to listen.
Now, I've never done and never plan to do drugs. But I wouldn't say any of the school's efforts to bring me to this conclusion were in any way successful. Hell, I'm the type of person who would be more likely to try drugs after having one of those presentations about how I shouldn't. I just think the schools and related anti-drug groups are going about their methods wrong.
Not to mention that most anti-drug PSAs tend to show even stuff like marijuana as super-deadly and dangerous, which I think is completely the wrong approach. Because a kid sees that then gets a friend who says "man, I've been using that stuff for years, they're lying out their asses about that shit killing people." Who's the kid going to believe, their friend of the PSA?