I think we are all drawn to people with joie de vivre and confidence, and we all want to be that person. In fact I am often told I am that person, 
which is news to me, as I never feel anywhere near as confident as people tell me I am, so I think I must put on a good act! But I think (or at least I hope) that that confidence doesn't always translate as being 'full of oneself' because that's very tedious for everyone else around you, although I am sure that all very confident people risk crossing that line at times.
It depends what you mean by confidence though. My DH says one of the reasons he loves me is because he can plonk me in a room full of strangers anywhere and no matter what they do or where they come from I can find some common ground with them, chat easily, make people laugh, and ask them lots about themselves, which is the way to get people to like you. When you are placed at a table next to someone you've never met before, and you reflect at the end of the night on whether you liked them, you base your opinion not on what you felt about them but on how they made you feel about yourself. There is a very fine balance between having something interesting to say, and holding court so that it becomes the Me Show, which will win you no fans.
If someone who has bombarded you all day with 'what's so great about me is....' is not going to make a very favourable impression. Whereas someone who has said 'What's so great about you....' is another matter. So long as they can find an angle that sounds sincere. I have mixed with lots of very polished and accomplished 'salesmen' types, highly skilled and successful networkers and political gameplayers. They all come across as having this incredible confidence and all the learned tricks of likability (asking all about you) but only the very, very clever ones manage to seem sincere. Or to remember a damn thing you've said to them next time they meet you. Because they don't really care about the answers to their questions - they don't ant to get to know you really, they are just going through the motions to make you love them, and I can see through most of them in two seconds flat.
My 'schtick' revolves around being self-deprecating and putting myself down a lot. Not in a depressing 'woe is me' way that has people looking over their shoulder for the nearest exit, but in a breezy, jokey way that makes people laugh but probably leaves them thinking I am being falsely modest about my own abilities. I don't know why I do it and I wish I didn't, but it's not an act - I mean it! I do have a pretty low opinion of my own abilities most of the time.
Self confidence can result in either arrogance or likability. The difference between likability and arrogance is the presence of a bit of humility. If that means I have to put myself down a little from time to time then I am okay with that. If it means I never rule an empire then I am okay with that too. No point being massively successful if everyone secretly thinks you're an arse.
Look at Xenia - I've never heard her utter a word that lacks conviction or confidence, nor show the tiniest shred of humility. She seems to have zero self-awareness or empathy. She is undoubtedly very successful and I admire her hugely. But would do I think I'd like her and do I want to be her? God, no.