I think there's a big difference between being arrogant and self-confident. I think self-confident people are sure of themselves, willing to give anything ago because they think they can probably make it work and are happy to sit back and listen to other people's conversations, or often ask other people questions about themselves.
I think arrogant people are self-confident as well in the sense that they're sure of themselves and their abilities, but always need to be the centre of attention, often try to show off how wonderful/smart/athletic they are, and are not interested in other people and their opinions.
I think when you're spending time or having a conversation with someone who is self-confident, then you'll end up feeling great about yourself and inspired by this person who is so sure of their abilities. When you're spending time with someone who is arrogant, you'll often end up feeling bad about yourself because arrogant people are often willing to belittle others to make themselves feel better.