Convincing my parents for me to get jaw surgery?

I'm 16 right now and i have a class 3 bite (underbite). I really want surgery when i'm older though but my parents are against it. They say "you look fine right now" "the surgery will scar your face and mess it up" "and you can die from surgery (even though the ortho said it is perfectly safe)" -_- I really want this surgery though! How do i convince them? Oh and also i heard that most insurance don't cover the surgery since it's considered "cosmetic surgery"... is this true? And i know that once I'm 18 I can make decisions for myself but i really want them to support me. What do i do?