That's because you assume the real world is partially constructed by civilization, society, culture, consciousnesses besides yourself.

That world certainly does exist, but it is not always hospitable for everyone that exists in it.

The real world is the real world, but altering your brain so the way various chemicals are metabolized and the way various neurons fire can often be not much different than getting sucked into a really good story, or having a pleasant conversation, starting a political movement, building a machine, etc.

It exists outside the boundary of contemporary social 'comfort zone', mostly because lots of people have war stories relating addictions, but causality is not always deterministic. A society that shuns a person because they do not fit 'the model' equally pushes people into coping with addictions.

Lots of people require different kinds of medication to get through life, day to day. Because someone is addicted to something does not mean to make assumptions about them or to show them disrespect, or to treat them with the conclusion that their behavior exists within a predefined and predictable boundary, of which you, the non addict, can clearly determine.

I'm sure there are lots of 'addicts' out there who want to be scientific about it, because they are actually trying to fix a problem that most of the world refuses to address, or even admit the existence of. The problem is that we experience consciousness subjectively. Outside of the range of operating heavy machinery, there is little tolerance for mental variation that differs 'enough' from the status quo, even though this is ridiculous to even begin to judge another person on.

If I experienced trauma as a child, who are you to tell me I can't take a medication that helps me feel warm, sleepy, and fuzzy when I fall asleep, instead of seeing nightmares flash across the back of my eyelids, as I close them? It is completely absurd that there exists whole movements dedicated to blaming the addict for choosing to take the drug, while completely ignoring the fact that no one in the world can change the fact that sometimes, bad things happen. People turn away from the world when they stop listening to it. Addicts are people that should be included in that set of 'the world', not merely judged because of some of your personal experience or biased statistics.