[offwhite]

"Why is that the significant measure of being ingrained in the social fabric?

Because those are the marijuana users.

"Seems to me having used in one's youth and later quit counts toward being ingrained in the social fabric."

Someone who tried pot once at a college party is hardly an example of "ingrained in the social fabric". In my opinion, it's rebellion against the social fabric that rejected it. Smoking marijuana has always been part of the sub-culture.

[ConservingFreedom]

Someone who tried pot once at a college party

I doubt that many of those lifetime-but-not-current users tried it only once - although I have no data on that.