Every driver is guilty of an act that can be blamed on a momentary lapse in judgment. You or I may make a proper lane change or legally proceed through an intersection 99 out of 100 times. However, the drivers who witness our mistakes may assume that we're hopelessly inept. It makes sense to give other drivers the benefit of the doubt. One reason is because it's earned.
Most drivers do a terrific job on the road.
A better reason for staying calm behind the wheel, is that cool-headed drivers make better decisions. They have a better chance of avoiding or minimizing accidents. Finally, you may run into serious problems if you cause an accident while acting too aggressive. There's a greater chance of causing serious injury and a higher likelihood of legal consequences. You also increase your chances of being sued.