Why people boast about themselves?

Well I think that people boast about themselves, is because they are jealous of you. There are some other reasons why this happens. One is because they have no life and want to cause people to share what they feel. Another reason is that they are so arrogant of themselves, or full of themselves that they have to boast about everything they do. It's making people feel bad about what they have done. Making the "Bullyer" look like a hero. Like today for example. I was enjoying myself in a little game of football in gym class right? So i threw some interceptions so what? Then I have members of the opposite team come over and yelled right in my face, "YEAH" or "WHAT?" or "You going to cry now?" I wanted to do something about it but i just let them because i knew they had no life at all. Being sore winners and keep on boasting in the locker room? Oh well. Just let them carry n with their lives and you carry on with yours.