i think in the situation you have AAyou definatly should not go all in on the flop when you still have so many chips left.
with everyone calling the chance of one pair being the best hand is tiny.

Everyone called before the flop. Not everyone can have a hand so its not that unlikely that you are up against a K7, K2, or trips.
By going all in you are taking away their chance to make a mistake because you will very rarely be called when you are winning if everyone else has missed the flop and you will always be called by 2 pair or better.

if your raise was to try and force missed hands to fold so they cant draw out on you then raising half of your stack will almost certainly do the same job and you may even be able to get away with less.
it sounds like you got very unlucky with being called by so many players but how big was your raise. If you only raised to twice the big blind then you are always going to get alot of callers. Otherwise you just got unlucky. In short there is no need at all to go all in early in a tournament with 8/9 people against you when you only hold 1 pair.