Why do we judge?

At first glance you can tell if you don't like a person just by the way they look. Too tall, too fat, too skinny. It doesn't matter what the reason is we will always find something about a person that we do not like. We have this preconceived idea that there is a certain way to look in this world and that will guarantee them an easy life. Even the prettiest girl can have the most troubles. There's this idea that looks and size is everything when in reality it's not even on the list. We judge because we wish we had what they had or looked the way they do. We push our insecurities on others because it is what we were taught to do. Would we judge someone who is a successful, educated and genuine person?