There's a saying: don't throw stones if you live in a glass house. The same human mind that rationalizes the intake of substances is the same one that rationalizes social networks, junk food, eating meat, whatever it is. I wouldn't be so quick to condescend.

At some point in time, it's important to realize that not everyone optimizes for longevity, correctness, rationalism, and so on, and they just simply do what makes them feel good within the limited life that they have.

Nothing is intrinsically harmless. Cannabis can be devastating. But I was just sitting here doing work one day, got a hemorrhage in my eye, and lost half the sight in it. Otherwise, I'm supremely healthy. The cause: a gene.