I wouldn't say most people eat meat. Current stats vary a bit due to how you define vegetarian but its somewhere between 20 and 50% of the entire world eat a vegetarian diet.
It might be a cultural difference in the meaning of the words, but here "missing out" implies a desire or intention to do something that never occurred.
i.e. missing out on something is considered an unhappy event to the person missing out which isn't relevant here since vegetarians don't want to eat meat.