Personally, I’ve noticed that the only people who think there are positive mental effects of pot are those people that are currently ingesting it. People who are drunk also think they are talking complete sense at the time…
The history (or lack)of marijuana in the Jewish world is not so important. What is important is its effects today. Today like alcoholism, marijuana use is primarily a form of escapism and I challenge anyone who is currently ingesting it, to try going 3 months without it and tell me I’m wrong.
I am not the type of person who gets upset at all the 13 year olds falling over drunk on Purim. I think its a mitzvah and more power to their parents for looking past societal conventions in favor of Halacha. But Purim is the exception to the rule like chagavim are exceptions to not eating bugs.