I’d note that being hit by a car doesn’t crush you typically, it merely transfers a lot of force and you hit the ground very hard. One of my best friends in high school was an unparalleled genius in everything he attempted - piano, chess, sports, math, everything. But he was hit by a car driving and hit his head on the curb. He has lived there rest of his life in the care of his parents with the mental capacity of a 5 year old.