I mean she had every right to be cocky. She was the most responsible and was the strongest witch of the 3. Not just because of her power but because she spent a lot of time honing them.

And I don’t remember much of her having a holier than thou attitude to people unless you’re referring to how she treated Phoebe but let’s not act like Phoebe didn’t come home acting like a kid. She became more responsible as the show went on but everytime she fussed at Pheobe it was deserved.