How can I stop comparing my life to my rich friends' lives?

I'm 17, and I always find myself comparing my life to that of my rich friends who come from upper-class families. Their lives, their enjoyment, and the things they post on Instagram and Snapchat make me feel sad deep inside. I'm from a middle-class family, and I know my parents can't afford that kind of life. They have big houses and cars because of their successful parents. Comparison has become normal for me, especially since my dad often compares my marks with those of my friends and our relatives' kids. I meditate, but how can I stop comparing myself to them?