It seems to me it would depend much more on IQ and the subtype of NPD much more than on the gender. For instance, if the narcissist is the somatic kind (gym & body image addicts) or even the classic grandiose one, it would make sense to find selfies almost exclusively on their social media. For the latter group, their selfies would be showing their social status, belongings, expensive clothes much more than their flesh. If they are communal, you would see them with people doing “good deads". If they are the ethical self-righteous narcissists, you would see them with family and friends to confirm the false persona. I know a narcissist who is the combination of a communal, self-righteous and oscillating between grandiose and vulnerable, overt and covert depending on how good or bad their circumstances are. If they are malignant, you would unlikely find them on social media. Foe this extremely dangerous kind who believe being GODS, being part of social media is downgrading them. They have much more subtle tools to get what they need from their victims.