I don't smoke pot, but I know several well-adjusted, successful professional people who smoke a little now and then. Some are grandparents-age. It's not just people who need to grow up doing it.
Same here.  When I saw that scene in POLTERGEIST, I thought it was funny (got a big laugh in the theatre) and real.  It was the first time I ever saw anyone other than teenage stoners smoking pot in a movie.