Why aren’t we allowed to be fans of ourself?

My theories

First theory:

Most of us are still victims of Christian morality which says: “Thou shalt not be prideful or proud of yourself”

Consumerist society?

Second theory:

Is it that American consumerist society tells us: “It is good to be a fan of someone else, because it will transform you into a good consumer”?

Consider, it is socially acceptable and actually desirable to be a fan of a certain sports team, tv show, actor, etc. But let us wonder:

Are the actors allowed to become fans of themselves? Or is this frowned upon?