A pointless phrase that is most often used on the internet.
It is used to whore for attention, because if someone is asking whether or not he or she is the only one, he or she should already know that the answer is "no," yet proceeds to ask anyway. Thus, "am I the only one" disguises a statement of
opinion as a question.
It is also used to convince oneself that one's
opinion is a unique, nonconformist take on things and everyone else are
sheep (or worse yet, sheeple).