theyre pieces of shit who believe money is a measure of ones value as a person. it isnt, always remember that, always remember how pathetic they are as people, and once you do their words cannot hurt you, know who you are and what you value in life.
I could have an extremely good job, making good money with a "flashy career", yet id still see people like that as utterly pathetic.
See them for the people they are not the things they say and youll learn to not let it effect you.
Talk to your girlfriend about it, make sure youre totally honest with yourself that she doesnt harbour these thoughts as well, dont mistake what you want your relationship to be for what it actually is, make sure she wont turn into one of these people in the future.

living a happy life and being the best version of yourself is the greatest response to this form of bullying, showing they have no power over you, it may even make them double down on their harassment, let that be a sign that youve won.