What is arrogance/humility, what is bragging, is it bad, and why?

[Xtreme2252]

I personally think it's good to be proud of your accomplishments. To me, arrogance is when you disregard other people's skills and accomplishments and disparage them and make excuses as to why others are lesser than yourself even though they've shown themselves to be equal or greater in a particular skill and have been humble about it.

For example, one of my friends is incredibly arrogant about League of Legends. He is Silver III with 600+ ranked games played in S4, and I'm Gold V with 300+ games played, yet he is jealous of me and blames his being stuck in Silver III on bad teammates and not himself, and he plays very selfishly, afk farming when he could group with his team and costing many matches he should be winning if he could be less self-centered.