Because they are not making a mistake by calling with weak Aces or gutshots or even a pocket pair. If I raise the flop, 2, 3, and obviously 4 outers are correct in calling a flop raise.

I'm not focusing on winning more bets, I trying to maximize my chance to win the pot.

Waiting till the turn is the only way you can do that.

Check out the examples is SSH, "When the pot gets extremely large."