To me, the point is that the claim "drugs are bad for society" is a problematic claim. Both from the standpoint that the word "drugs" is poorly defined when in reality there exists a broad spectrum of drugs/effects, and because to your point, the experience of using these drugs is subjective/varied, and can't be considered universally "good" or "bad".

You're gonna fall ill or die if you drink too much water.

If you know too much coffee is bad for you why on earth would you even drink so much after the first couple of experiments?