Insults are hurled because the “hurler'” instinctively knows it’s gonna hurt us. They peer into our psyche and conclude that that whatever they will say or do will sting.
They conclude that we dislike not having enough and strive to make more money. They trust that fat people tend to hate themselves and that people of certain races bemoan their origins, hence, they will fire these bullets with the intent to bring us down emotionally.
You see, every insult or snide comment based on superiority complex always make an assumption of share values - that we believe what they believe. Try throwing pennies at a man who does not believe he is poor. Or you may try calling a woman a nasty nickname you just learnt from a show she does not watch and you will that confused look that tells you your jibe just lost its sting.