I think this is a big part of it as well, though it's hardly unique. I don't think it's the whole story as what I'm describing does not only apply to drugs. In various times and places it has applied to music (jazz, rock, electronic at different times), dancing, sex, food, playing sports, and really just about any pleasurable activity. I think perhaps some of the Puritan roots are just all too alive and well. Also, it's not so much about thought but about feelings. That's why no one usually says it out loud. Also, I think the people that think in this way are aware of what they're thinking to some extent and in many cases, even realize the negative intent they're wishing upon others.