Thank you.
And there are different types of psychological addiction, too. Some involve fulfilling some psychological need that is seriously neglected, others actually create a de-facto chemical addiction by triggering strong reactions from your own body. And to complicate it, some addictive activities can be either or both. For example, an MMO could provide a sense of social connection to a member of a guild that is severely lonely in real life, or it could create a feedback loop of endorphins, ala the Skinner box, which are a potentially addictive chemical. Same activity, completely different forms of addiction.