Well, because you're a normal human being. You might find this an interesting read:
The Presentation of the Self in Everyday Life. Ervin Goffman.
(extract from Wikipedia summary):
The Presentation of Self in Everyday Life was the first book to treat face-to-face interaction as a subject of sociological study. Goffman treated it as a kind of report in which he frames out the theatrical performance that applies to face-to-face interactions.
[3] He believed that when an individual comes in contact with other people, that individual will attempt to control or guide the impression that others might make of him by changing or fixing his or her setting, appearance and manner. At the same time, the person the individual is interacting with is trying to form and obtain information about the individual.
[4]
Goffman also believed that all participants in social interactions are engaged in certain practices to avoid being
embarrassed or embarrassing others. This led to Goffman's
dramaturgical analysis. Goffman saw a connection between the kinds of acts that people put on in their daily life and theatrical performances.
In social interaction, as in theatrical performance, there is a front region where the “actors” (individuals) are on stage in front of the audiences. This is where the positive aspect of the idea of self and desired impressions are highlighted. There is also a back region or stage that can also be considered as a hidden or private place where individuals can be themselves and set aside their role or identity in society.
[5]
The core of Goffman's analysis lies in this relationship between
performance and life. Unlike other writers who have used this metaphor, Goffman seems to take all elements of acting into consideration: an actor performs on a setting which is constructed of a stage and a backstage; the props in both settings direct his action; he is being watched by an
audience, but at the same time he is an audience for his viewers' play.