Healthy self-esteem is one thing, and to be admired. Conceit and unfounded over-confidence is another. That's what we're looking at here.
Jade has a glaring vulnerability though - she has a very expressive face and you can see every unguarded emotion. I recall on launch night a distasteful look [I think it was highlighted on Bots] when someone else attractive came down the stairs.
And tonight, when Jack was facing his decision, there was absolute horror and panic on her face that he might accept and there would be no dosh.
She also gave away her flaky nature in the task, frightened a balloon might hurt her.
I think she's much more mercenary than anyone else in the House.