One obvious way to win money in a hand is to have the best hand at showdown. One of the best ways to have the best hand at showdown is to get hands that might beat you to fold pre-flop.

When you have AA, what kinds of hands do you want to call you, preflop? You want AK, AQ, KK, QQ, JJ type hands in the pot. Your hand dominates them and it is likely that you will have the best hand at showdown. Further, for hands like AK and AQ, the board can even make them think they hit something and you still have them beat.

When you have AA, what kinds of hands do you NOT want to call you, preflop? Medium suited connectors. They have the best chance of beating an AA. What hand works best against AA? 65s where the suit does not overlap the suit of either Ace. Yes, 65s has the highest chance of beating AA with odds of 3.34:1. Compare that to the odds of KK vs AA, 4.54:1. Compare that to the odds of AK vs AA, 11.26:1. Not only is 65s the most likely hand to crack AA, it has another enormous advantage. It is incredibly easy to fold if the flop misses (unlike KK, AK). So, the 65s hands are not going to call your bets after the flop unless they have a good chance of beating you (or already have you beat).

So, to have the best hand at showdown, it would be wise to bet enough preflop so that only really strong hands call; which, in turn, your AA dominates. With fewer callers, suited connectors in late position are not getting the multiway pot (and the implied odds) that they need to make a call worthwhile.