It's really not, the people that don't have it are flipping man! I wonder how somebody could be so relaxed in such situations, they are either stupid or think that they are some type of superior being or something, we must study them and discover why they are so screwed up, which they really are, never trust a relaxed happy person, they are either really dumb or just don't give a damn about anything, probably both. Now, the cause of social anxiety, is simply just awareness, do you really want to be one of those people, because they are horrible people, im not blaming them but holy crap are they horrible, a little advice, stay shy, crush your ego, and oh my god exercise your loving and intelligent anxieties because you will be a better person.