Call me the odd one. But I disagree with the (very) common notion that people who constantly selfies themselves are "insecure".
I wrote numerous times that I am against social media (still in a lot aspects) when money, fame and wide-spread status-seeking are altogether involved. But within the context of sharing and exhibiting your freewill as an individual, especially if one is very much indeed considered themselves to be attractive or good looking; I see nothing wrong with it.
Let's face it, we are all attracted to an ideal "set" of qualities. And most of these as much as most don't wish to admit - are mostly external. Why? because it's the very first thing we gather indirectly about such a person. There is always a grain of truth to why these people feel the "want" to express how good looking they are. Of course, what sort of truth that is remains personal. Some express it freely for the sake of personal fame. Some express it freely to promote an ideal fitness image - through lifestyle & commitment (Jen Selter, bodyrock.tv, basebodybabes, etc).
Again, I don't think there's anything wrong in flaunting yourself if you believe yourself as good looking. Once expressed within the right frame of mind & substance, anyone would do it.
Hence,all this trend to me - fits in the context & simple purpose of attracting and tittilating one another just fine. Why? it's just a reminder part of human nature on things we just simply find attractive. I see nothing wrong with it.