One of my most vivid memories from high school is my science teacher becoming very vehement and emphatic in warning us never to smoke pot. I believe the basis was the "gateway drug" theory.
Some 20 years or so later, in the 1970's I was living in DC and got selected for jury duty. At that time we reported to the judicial building every work day for a month and sat around waiting to be called. One of the trials I was called for related to marijuana, don't remember whether it was for possession or sales. I asked to be excused from serving on the jury, basing my request on an objection to our marijuana laws. The request was granted.
I don't remember my views on marijuana laws. I think I gradually came to support the downgrading of the penalties for possession to a simple ticket, like a traffic violation. But I think I've always been reluctant to support legalization. My puritan ethic cautions against it.
Today it seems the nation supports legalization. Certainly the Democratic candidates support it.
Personally I'd feel more comfortable if we held off on national legislation, allowing the various states to do their thing, testing various approaches to legalization and control over the market, taation, etc.