I am a healthy weight. I exercise regularly and eat a balanced diet, and I dont have any medical conditions, so when Friday rolls around and my DH suggests a big greasy take away, I say "hell yeah". I eat it and enjoy it. Then Saturday morning comes and I head out for a run, and have muesli for breakfast. Life continues as normal. I don't get fat, I don't develop a health condition and I don't end up eating take away every night. I eat normally.
The thing that some people on this thread don't seem to understand is that for a lot of people, this is what their marijuana use looks like. They dont have mental health problems, they are generally happy and fullfilled, they have a nice family life and a good career, and then their mate texts them one day and says "hey, heard your kids are at their grandma's this weekend, fancy coming over to watch a film and have some space cakes?" And they say "sure, sounds fun!". And so they do it, they have a good giggle with their mates, and then they wake up the next morning and continue with their normal lives. They don't develop mental health problems, they don't start doing it every day, and they don't become a shadow of their former self. They just carry on as normal, and probably don't even think about it again for weeks or months, maybe longer.
I know that this isn't everyone's experience. I know that for some people they get addicted they have mental health problems and it ruins their lives. But we need to accept that this isn't the case for everyone. Just like it's not the case that everyone who has ever eaten a greasy Chinese take away gets addicted to junk food and gets fat.