oblivisumption
A niave assumption rooted in denial, insensitivity, or grandiosity that everyone engages in an activity in the same manner as one does such as obliviously assuming all people drink or use drugs with impunity.
She made the oblivisumption that the party hosts would appreciate a bottle of wine as a gift because everyone appreciates alcohol as a gift. An arrogant or oblivious attitude drinkers or substance users sometimes possess that disreagrds the 20-30% of the population suffering from addiction, are in recovery, or simply do not drink or use drugs. Such absent-minded or arrogant presuppositions may lead to bringing alcohol to a dinnerparty hosted by recovering alcoholics or smoking marijuana within the same clean air space of a drug-free individual.