As I was saying, it's not as if smoking weed suddenly causes life to cease.
They don't even claim that.
Anti-pot propaganda uses these three points incessantly:
- Marijuana decreases attention span in the long-term, meaning after years of use.
- Marijuana is a gateway drug to Cocaine and Methamphetamine.
- Marijuana is illegal, so you shouldn't do it.
The first is just totally unfounded. People who do drugs in the first place have some sort of need that is fulfilled by it. Marijuana is used in some states as a treatment for ADD, and while many comedians like to poke fun at this I doubt some scientist pulled "POT IS GOOD FOR ADD" out of his ass and a large enough portion of the scientific community backed him for stuffs and giggles. Chances are, the people who are using pot long-term (e.g. after it's something cool and they gain actual responsibility) are self-medicating and this reduced attention span is simply their normal mental capacity.
As for gateway drugs, that's pretty much their admission that pot has no measurable downsides and that the only thing left to do is scare people by saying "if you smoke pot even once you'll be a crack whore by next Tuesday." It's likely that the only evidence they've found that correlates this are in the kinds of people who submit to peer pressure all the loving time, bought into pot because someone suggested it, and when another friend passed them a crack rock they did that, too.
You probably came to the conclusion as soon as you read point #3 that the only reason it's illegal is because the government says it is. If the illegality status was lifted, this would no longer be a problem.