One thing I observed [long ago] was that individuals who used marijuana had something they were admittedly trying to escape. The marijuana "mellowed them out" so they could contend with the circumstance more equitably. The thing they regretted was that the mellowness was not discriminating, consequently, things they wanted to have motivated drive for were sedated along with the problems.
My observations match those of other editors. The kind of students who I was with who smoked marijuana were either discontented rich kids or otherwise unmotivated and listless individuals. It is thus very hard to say that this was a behaviour caused by smoking marijuana as they already displayed this behaviour in the first place. To what extent it exacerbated such behaviour is a matter of debate.
I agree with the previous posts. I've never tried marijuana myself, but I've seen the effects it has had on some of my students. Maybe the folks who used it occasionally were the ones I never even knew were using it. In some cases, however, I have had students whose use of it was pretty obvious, and I will simply say that they tended not to be good students. They were often listless, unfocused, unmotivated, and under-performers.
I too never smoked myself, so I hesitate to speak with any kind of authority. But I have seen some of what previous people have mentioned, some folks that tried it, enjoyed it and moved on later and others that have made it more of a habit.
For some it becomes an obstacle to things like steady employment or a healthy outlook on life, but for others it really just seems to be something they enjoy and that has little negative effect on their lives.
What I've noticed most about people who do drugs is that it alters their personality, often turning a sweet, mellow, agreeable, personable person into someone who's belligerent, rebellious, unreasonable, and antagonistic. Drugs seem to make a person less responsible and reliable, too. My son did marijuana for a while and went through about sixteen jobs during that time. He was very hard to get along with and that, coupled with the fact that most employers don't want to employ someone who's under the influence of drugs, kept him from being a good employee. He also got booted out of the Army, lost his bonus, and is still paying for it years later! So, I don't see any benefits coming from using marijuana.
I've known a number of students over the years who have used marijuana regularly, and some who came high to my class. I have seen relatively bright students who suddenly didn't care about their grades, friends or much of anything else. The effects may not be as dramatic as with alcohol or other hard drugs, but the side effects are still serious nonetheless.
I knew an acquaintance in college (1980's) who was CONVINCED that his marijuana use "opened his mind to his creativity" -- and he was a graduate student working towards a master's degree in creative writing. Sadly, the marijuana just seemed to leave him stoned and unmotivated -- waiting for the spirit to move him, so to speak. He never finished the degree and he has never written successfully -- he currently drives a truck for UPS. I can't say the marijuana is the cause, but it certainly didn't help as much as he thought it did.
Although I never experimented with it myself, my friends and acquaintances who did so (in the 1960's) seemed to be going through a typical rebellious stage which one often experiences in ones late teens and early twenties. Many of them later became professional men and women and have done quite well. Others were not so successful, and had issues with substance abuse. However, the same can be said of my friends and acquaintances who never touched it. So, I think it is a reach to say that marijuana use leads to other addiction problems, although one who is prone to addiction may very well become addicted to it or some other mood altering substance such as alcohol or tobacco.
It's hard to know what is the cause and what is the effect, but my friends who smoked marijuana (at least the ones I knew about) were the people who were not as motivated. These were people who didn't really care much about how they did in school. Again, though, I can't say if the marijuana caused it or if both marijuana use and lack of motivation were caused by something else.
I know a lot of people who smoked marijuana in the past and they no longer do. Here are my two observations. For some of them, they are completely fine. It was a time in their lives where they experimented and they stopped when they got older. There seems to be no adverse effects. Others went deeper into drugs and now their lives are no longer the same. They lost intelligence, motivation, and drive. They seem to be fundamentally different people. In light of this, it is certainly best not to start at all.