People around you can say something insulting to you without realizing they hit a nerve. Even if they do it on purpose you can make a scene if you confront them (First time, I wouldn’t, if they make a habit out of it, I will confront them). Sometimes it’s good to write your angry thoughts down to get them out of your mind. So, you don’t end up saying something you might regret and so you can spend more time on positive thoughts than negative thoughts.