Despite common perception weed doesn't make everyone mellow and happy. I'll site 2 personal examples.
Me: Paranoia. I'm 44. Never been much of a drinker and only smoked pot a handful of times a long time ago. The last time made me quit completely. I was at a friends having dinner and playing some games ala Wil Weaton but a long time ago. The joint started to go around and unusually I joined in. I felt it creeping up on me right away. The feeling that everyone was watching me, waiting for me to make a mistake. Ready to pounce. I left a few hours later. It was 11:30. My apartment was 2 miles away. It took me an hour to get home. I was driving at <5mph the whole way and took only "back" roads including many unnecessary turns. My 3rd floor walkup apartment has a tiny balcony overlooking the corner gas station across the street. I'm sitting at my kitchen table wound tighter than I've ever been when the alarm at the gas station goes off. It is ear splitting (interestingly that was the only time it ever went off). EVERY cop in town shows up (it's not that big a town). Flashing lights are everywhere. I have blocked the door with the refridgerator and spend the night sleeping under the bed. Yeah, pot and I do not agree.
My stepson: Asshole. My youngest stepson was the coolest little kid and teenager I've every known. Most kids (including me) become sullen jerks as they enter the teenage years. My two oldest step kids did (I love them all!) but our youngest was awesome. Watching stupid comedies like "Jay and Silent Bob Strike Back (2001)" was awesome. He was so full of life. he was never going to be a rocket scientist but he was definitely the kind of guy you wanted to be around. He wasn't a looker but the girls loved him. He wasn't much of an athlete but he made varsity because the coaches liked him. He wasn't a great student but his teachers adored him and he was usually in some trouble (minor pranks, skipping, etc.) but the principal was his pal. I know it probably sounds like I'm exaggerating but everyone I talk to even 10 years later agrees with my memory. I can tell you when he started smoking pot. He was 15years 9months. Overnight he became an asshole. His grades dropped, he quit football. He withdrew and stopped taking care of himself. Looking back I wish we had taken more drastic actions but at the time the only thing I could think to do was drug test him. He tested positive for pot and nothing else. We talked about it but his mom and I didn't think pot was the cause and it must be a phase. 12 years later it's still a phase. He's still smoking pot and he's still an asshole. Every now and then he'll stop for awhile and that wonderful light we'll peak through. I miss him. I see him all the time but I miss that light dearly.
I think our pot laws and punishment are ridiculous and our drug policy is an utter failure but I do agree with Nancy Reagen (God of all people). Drugs are bad. They may make you feel good. They may make you more popular with your friends (the ones who also use drugs anyways) but they won't help the people who love you. They won't help you be a better person or parent and they won't make your life better in the long run.
/sorry, it's a painfully sore subject for me right now.