Announcing too early?

I'm not pregnant yet but when I do get pregnant I know I'm going to want to take that test and show it to everyone and their mothers. I was curious on why people wait 12+ weeks to announce? I know its probably because the risk of miscarriage but the way I think either way it's your baby and I wouldn't want to hide my child from the world. Maybe I don't understand because I have not lost a child but I would really like some feedback because I'm curious.