Yes you are right there is no betting starting hand in poker but some poker players have a very difficult time when it comes to folding pocket aces. All poker hands lose at some point below are a few statistics,

• AA will lose approx. 12.5% of the time against 72
• AA will lose approx. 23% of the time against suited connectors like 67
• AA will lose approx 13.5% of the time against 22

Pocket aces can lead you into all sorts of trouble for example, your opponent could be sat with a small pocket pair like 22 and the flop comes out Q,7,2 and it's a "no-draw" board then you will find yourself running into some big trouble as an obscure flop like that would make it very hard to detect the trouble. This is why playing small pair can sometimes be very profitable.

If you are dealt AA and the flop comes out as 6h7h8c then maybe think twice before rushing to call an all in bet as your opponent could easily have a much better hand leaving you drawing virtually dead. Try to spot the danger flops and maybe instead of re-raising just call the bets, that way if the bets get way too large or you see another card connected to the straight or flush then you can fold without losing your whole chip stack.

When playing and you suspect another poker player of having AA try calling if you have low suited connectors because if you do hit a "monster" or the "nuts" on the flop, you can virtually guarantee a double-up.

Pocket aces can avoid some of the "suck-outs" by raising all in before the flop which will make it very hard for someone to call with a small pair or low suited connectors, this would leave anyone with AK or AQ seriously considering the call which is the best situation for pocket aces as AA completely dominates both of those hands.