James Joyce once said something along the line of: in art, that which we desire to possess is pornography; that which we reject becomes didactics. I think the phenomenon of "selfies" relates more to social pornography than any desire for immortality through spacetime capture.
Yes, immortality through spacetime capture is more about actors and artists, Lady Gaga etc. In more average people it's a sort of social instinct, as captured nicely in the movie (and book, I assume) The Circle. Things just seem so pointless now if they're for your eyes only.
I think it might have something to do with people really being social beings that used to live in closely knit groups, with relatives and children and everything, your small group was your entire world and everybody knew about you and you about them, and so you were, in a sense, the center of the universe, along with your group. Whereas now, the group is HUGE. And people feel a kind of meaninglessness if everybody doesn't know them. That may be where the desire for fame partly comes from. A sort of nihilism seeps in once you realize that there's so many people out there for whom you don't even exist, and you hasten to correct for that by plastering your face all over the social media, trying to wind your mind back to that primitive but natural state, where you knew everybody and everybody knew you.