That is to say, the problem with porn is not that it makes men into worse and worse consumers as time goes on due to an addiction effect, it's that porn - like any other kind of exposure to any other kind of thing- teaches your brin patterns. If you see violence on television, your brain becomes inured to the horrificness of violence. SImilarly with porn, when teens start viewing porn - as has become more common over the past few decades with earlier exposure to these kinds of media - the behavior portrayed is normalized - thus the increasing normalization, for example, of anal sex and "cum shots" in a woman's face for example, as normative behavior. This leads to a cycle in which what becomes normal is more and more outre. There's lots of good sociological work on this out there.
Porn doesn't act like a drug, it acts like a mentor...