I wouldn't care either if I were you, especially if you don't know the people. But I wouldn't take it personally; they're not "rubbing their success in [your] face". If I know the people, I care if they are happy; whether that is buying a new house, having a baby, getting married, getting a promotion. If it's something they want, great! But their life is no reflection on my life and what I want.

One can't have friends or loving relationships if one doesn't care about the other. All the rest one can be neutral about but not the one in one's life. Negativity about others who inhabit one's life is really just negativity about one's self. What do you want "better"? You have to practice whatever it is.