Most three-year-olds think that the entire world revolves around them. After all, it seems that way because Mommy gives them a cookie if they want one, and they get to watch Elmo on TV all day long just because it’s their favorite show.
Who cares what anyone else wants to see, right? Elmo is better. That’s just how it works. This behavior is excusable because they’re children. They simply don’t know any better.
Teenagers are actually another good example. They should know better, but they still expect things from their parents because … well, their friends all have the coolest new phones and computers and clothes and cars, so they should have it all, too … right?