Random violence has to be the scariest creation of humanity.
In nature, violence has a purpose, usually related to feeding or mating. Only human beings practice injurious or lethal ambush as sport or even casual diversion.
Read this account of a commuting cyclist shot in the lung and heart near his home in Seattle. The weapon was apparently a bb shot from a .22 caliber gun. With a larger charge behind it than typically provided by an air gun, the projectiles actually penetrated his chest, puncturing one lung and hitting his aorta.
Motorists shoot each other, so this isn't just a hazard of cycling. It's a sad truth about human beings. Some of us are stupid or callous enough to consider violence to be comical. The comment thread after the cyclist's blog post includes other people's accounts of assault with various things ranging from the usual rocks and bottles to food.
Cyclists make a tempting target because we're out there in view, unshelled. The kind of people who like to pick on someone they perceive as weaker see our slower pace and lack of armor as an invitation. We can't wear a Kevlar vest all the time, in case one of these reprehensible morons comes along. We can't quit cycling. That would be like quitting driving because some day or night a drunk driver might come across the centerline at you, or some enraged driver might shoot you. Yes they might. If they have no conscience or the one they have loses its battle against their darker impulses, you could come out the worse for it.
This is the world we live in. As unfair as it is, these are the people we could die of. No war except the personal war against one's own impulses to lash out will ever change that. Punishment may do no more than breed a greater resentment. Whatever satisfaction one may get from hunting down a specific perpetrator and penalizing them, it does little to change the kind of mentality that would do such a thing in the first place.
You might as well ride.