A king is not a king if he is not confident. [He says this in a way that comes off as both entirely arrogant and extremely practiced. Apparently, he's either expected Karna to say this, or he's heard it been said before.]

And it is an attractive trait for any one person to have.

If you do not show confidence, you do not have the power to have others look up to you. Regardless of what it is you're confident about.

[And now he smirks, an almost playful look on the pharaoh's face.]

But aside from that, if you'd like to see why I am so confident, then perhaps you should share my bed with me tonight.