Just like getting hit by a car happens almost never? Anecdotally, I have never been hit by a car, but have fallen off my bike multiple times for a variety of reasons: bike entered the lane without warning while I was going downhill, I hit a rock on the road, front tire got caught in a groove in the road, …

Falling off because of gravel on the road, grooved surface or other road hazards sounds too much like inattentive riding or speed unsuited to road conditions. A helmet would help in those cases, but better attention to the road would also be a good idea.