Well, it's alright if they fall out. It's not very enjoyable when your orthodontist tears out your loose tooth, though.

Because they've already separated from the rest of you, they're pretty much just stuck until they get pushed out by the growing new one. And it's celebrated by kids because every kid wants to "get big" and "grow up", and bigger, stronger teeth are seen as a sign of growing up.

Therefore, your argument is fail.

If you lose your teeth a second time, it's a sign of you growing old.

EDIT: It wasn't supposed to be an arguement.

Well my family used to celebrate me losing my teeth I got money and i see it as a sign of someone geting older and out of the class of just being a little kid and being a big kid. Well that just my oppinon

Well, there's the "Tooth Fairy." They expect to get money when it happens.

yuo gett cash!1

Knowing you have another set of teeth growing in is always reassuring. Every now and then I have dreams where I lose one of my adult teeth, and it always freaks me out in the dream, and then I wake up and go, "Uh, what happened?"