Some studies have claimed that narcissists are more likely to take selfies than ordinary people. A narcissist always looks for ways to satisfy his ego and feed his desire for superiority. A selfie allows the narcissist to fulfill that desire.
Sometimes the main reason someone posts a selfie is the need for approval of their looks. When some people feel like they need a self-esteem boost they post a selfie to get some likes and comments that will make them feel loved.
Some studies claimed that people who take selfies often are not really satisfied with their looks and that they attempt to take many pictures from many angles until they find the perfect angle that makes them look good. (See also why women make duck faces in selfies).
People who keep taking selfies might be perfectionists who keep repeating the same task over and over, looking for the perfection they never find. Perfectionism might be a sign of low self-esteem.
Sometimes selfies are taken with a social goal in mind. The person who holds the phone and takes the picture of the whole group can be sending an indirect message that he is loved by everyone or that he is the group leader.
Some studies claim that people who take a lot of selfies are very likely to be mentally unstable. A connection was found between the habit of taking many selfies and some psychopathic traits.
A person who takes so many selfies is usually very obsessed with looks. This kind of obsession can backfire because it can easily force that person to get dissatisfied with his own looks. Usually, a person who focuses on something too much ends up suffering because of it.
People who rarely post pictures with others are very likely to be self-centered. If the selfies a person takes show no one but themselves, you might be dealing with a self-centered person (See why some people are attention seekers).
People who keep taking different photos from different angles until they find a good angle are more likely to have self-deception tendencies.
If a person takes a selfie once in a while then this might not indicate the presence of any psychopathic traits. However, people who take selfies very often are very likely to be mentally unstable.
People who take selfies very often might be attention Seekers who just want to draw some attention to themselves by posing, or by posting good looking pictures. A selfie can be a cry for attention.