We know there is an effect. That's why people use them. Seems to miss the point to just say "this is harm" and ignore whatever factors would influence the decision to use.
Why is that prescription drugs come with a long list of "side effects" but most of society doesn't see the "harm" in those?
I imagine a lot of it is due to many prescription drugs not being habit forming or generally pleasurable, thus people are more likely to use it in cases where the benefit outweighs the harm in a much more objective fashion.
Your answer just further illustrates my point.
Have you ever been cycled through different antidepressants? Anti anxiety meds? ADHD meds? Meds for sleep, meds for wakefulness?
These drugs are all very potent and your body cannot distinguish between intended and so-called "side" effects.