They may feel nervous because they are showing who they are as a person. Most people have a fake image of them selves when they are in public. For example If someone has a friend and they have done some things they do not want to share they might make a fake image of themselves to make it seem like they would have done those things.
This impacts their own self image because they are faking who they are and they feel that if they show someone who they truly are something bad might happen to their image and reputation and including everything they have built up in that fake image.
