One's bias towards their own opinion—as a result of being the
original poster, sender, or
equivalent—on
social media forums, especially when accompanied by a sense of self-confidence or entitlement by the sole act of sharing their opinion on said social platform.
Why was the sender supremacist certain that
the Earth is flat? Well, it's because he sent it.
Reddit is widely
considered to be the best example of sender supremacy. Either your viewpoints must entirely align with that of the sender, or you are cast off as an unknowledgeable
internet troll and promptly downvoted to oblivion.