In those times when Christ talked about how we should live our lives being arrogant wasn’t one of the characteristics he mentioned, just the opposite. There’s not a problem with being confident which is basically being self-assured because that’s a characteristic of someone who is successful but arrogance is revealing an exaggerated sense of one's own importance or abilities. One of the key words here is “revealing” which is also known as bragging.
So the bottom line is we’re called to be humble not arrogant. People don’t like being around arrogant people and how can we make a positive difference in this world if people don’t want to be around us?