i always thought the point of smoking weed or taking psychedelics was to get hallucinations. weed is actually a psychedelic drug so i think it's normal to get hallucinations. if the person is starting to confuse the hallucinations with reality i think it can be a pretty big deal/problem, but if not and they aren't driving around endandgering other people hallucinating i don't think it's that big of a deal.. you didn't really describe too much about their situation though, so i can see how there could be problems or you think it's a problem. you didn't say whether or not it's auditory or visual hallucinations as well. the person might be a schizophrenic. some schizophrenic people like being schizophrenic though, so it's hard to judge and say what the person should do.