Not good at quoting and responding but I'd like to address a few things mentioned.
First, some of the students I now have, that presently cut all the time and are failing miserably, were previously good students. I've had them before. Actually wondered what the change was all about until I started noticing they reaked of pot all the time.
Second, I find it interesting to think that people's marijuana use doesn't affect anyone else. It absolutely does, in many ways. When people are stoned the mass majority of them are disconnected. Kind of in another dimension not relating to things on the same plane as I am. Everybody knows the dumb smile that often accompanies being stoned, and the familiar "dude, it's all good" attitude. Was doing some studio work not that long ago. Engineer got toasted mid session and then laughed when he just spaced out and completely lost where we were. More than once. "Sorry man, I'm tired and spacin out." It also affects me on a much higher level with what it's doing to society. There are an unbelievable amount of kids just hanging around the streets where I work, just getting burnt out and doing nothing. You can say all you want regarding that having to do with the individual, but I swear to you a lot of these kids were OK before they were getting high every day. It's the exception, and I'm sure there's a handful, who aren't affected in a negative way. I can get long winded about how others pot smoking affects me, but I want to move and address other things.
The gateway drug. Yeah, it's cliche, and it's been laughed at for decades, but I completely disagree with people who say it's bull. Or the same as alcohol. In order to buy and smoke weed, you have to cross a line. The legal line. You have to buy it through a dealer and those dealers are more often than not selling other drugs. If not, they can offer easy access to them. The door is open, and when kids get bored with pot and just want to go a little further, they do. Its readily available, and they don't have to think too much about it, go out finding source for it, etc. Discount it if you like, but it's a fact.
Last note for now is that while pot "seems" harmless to the countless people who are smoking it on a regular basis, and while it definitely affects people differently, there is no denying that after frequent use some people pay severely in later life. After the damage is done. There is such a thing as marijuana induced schizophrenia. I've seen it. I've also seen many people who wound up with panic and anxiety disorders as a direct result of their smoking pot. Depression is another common side affect. And lots of these things are easily written off as caused by something else. Pot not even being brought into the equation because, well, people aren't going to want to stop.
As for being addictive that's tricky. I don't believe there's any known physical addiction, but I'm certain people get addicted to it same as they can to other drugs, or obsessive behavior. People with emphysema take cigarettes to their graves, and trust me it's not an addiction to nicotine that's killing them. If it were, the gum and patches would work. There are marijuana addicts meetings (MAA) all over the US that will tell you differently if you tell them they aren't addicted. Addiction is next to impossible to define however. The clearest definition for someone would probably come only if they had a good reason to stop smoking, and found they couldn't. Most pot smokers feel the benefits outweigh any of the hazards so there's little if any motivation to investigating whether they're addicted or not. In my opinion someone smoking 2X a week has an addiction. Especially if they're putting their job at risk (which in most cases they are), and even more so if they have families that they want to have healthy relationships with. I think that getting busted for pot would probably have an all round negative affect for the loved ones sourrounding a pot smoker. A teacher I know was suspended from work for year pending hearings because she was in a car accident and pot was found in the car.
Post is getting too long so I'll cut it for now.