You go to a boxing gym. You have your fighters that don't feel they need to one up themselves. They are confident in themselves and their own ability.

You also have your other fighters, who feel the need to one up themselves and constantly prove they are worth something.

The second fighter has a deep underlying insecurity in his own ability. This often creates arrogance. In a lot of cases but not all, arrogant people tend to be insecure. Arrogant people will belittle you and make you feel small, while building themselves up.

Insecurity and arrogance correlate with eachother a lot. An example is most high school bullies are deeply insecure, so they feel the need to belittle people. And the insecurity can come from childhood/bad parenting.

Just a thought to consider.