In a two person game, one should try to make the "best moves." (If your opponent doesn't, you'll crush him unless the dice or other luck factors go very much against you.) That's not always true in a multiperson game.
In Diplomacy (which I know better), the player that goes from three to six cities in the first year becomes an obvious target. (Russia, which goes from four to six is the most frequent winner, but the second most frequent loser.) So in the beginning it's better to keep a low profile, do good but not great, let other players fight it out for half to two two-thirds of the game, and make a "run" toward the end.
Could a similar dynamic be at work in Settlers of Catan? That is, you want to do well enough in the beginning to "keep up with the pack," and yet not so well that other players see you as a threat and gang up on you? Is it even possible that bad play (or bad dice) in the beginning will generate a "sympathy" or "no threat" factor that will cause other players to treat you well later on? And is one way is to get ahead quietly by accumulating good cards instead of good hexes?
It's impossible to pre-arrange this, but if I could, I'd arrange to have all my bad die rolls in the beginning and the good ones at the end so I could be "non-threatening in the beginning, and make a surge at the end. Are there other ways to accomplish this in the game?