Porn addiction isn't a thing. It's made-up bullshit by people that buy into Judeo-Christian morality regarding sexual "purity". There are reasons that it didn't make it into DSM-V, and won't make it into DSM-VI either. The porn and masturbation isn't the problem, it's how people feel about it, and how they reconcile it with their own beliefs in morality, which is not even remotely the same as being addicted to opiates or nicotine.