No I do not believe all confident people are arrogant, in fact I think the opposite may be true. Arrogant people sometimes act arrogant in order to hide their insecurity, inferiority, and a lack of confidence. In other words, it’s a way for people with low confidence to protect their own egos and prevent them from being hurt by others.
Demonstrating arrogance is also sometimes a way for people to get attention and gain approval from others to help build up their self-confidence. Unfortunately in doing so, they often treat others badly.