Here's what I think: She's was never your friend. She might be blood, but she's not your friend. Deep down she's envious that your parents don't live off the government and can legitimately do it for yourselves and is likely ashamed of her parents behavior. She might make all this money out of school with her big paying job, but it's all artificial pomp and circumstance, and she knows it. She's likely going to have to buy all of this stuff for her parents, maserati or whatever, because she knows there's nothing there for their future. She's supporting them now and while she's boasting, she's probably deep down pretty ticked off that they have nothing of their own, and she's now their financial support to abuse. You can buy whatever you want because you were raised to do so and have earned it yourself, as have your parents. And she's built up this wall of BS around her, despite the fact that you're family, that she knows she can't climb because she's so worried about what people will think if she admits that defeat. Be proud of your accomplishments, and let her figure out her own childish nonsense for herself.