In over 30 years of helping injured people receive fair compensation in auto accident injury cases, I have also been called upon to represent many bicyclists hit by cars. These injuries are often severe as you might imagine. Insurance companies usually believe the injuries and seem more "generous" in settling these cases.
Of course, no one wants to suffer a permanent injury. Money can compensate but does not restore health and bodily function.
Injured bones and muscles are one thing, but brain injury is quite another. The suffering I see in my brain injured clients effects all aspects of their lives and degrades quality of life across the board.
Do bicycle helmets help avoid, or mitigate brain injury? Yes they do! I highly recommend the article "A Heads up for Cyclists" in the Consumer Reports magazine, June, 2015. There is clear evidence that bike helmets can reduce fatalities and concussions.
Consumer Reports quotes Dr. Frederich P. Rivara, M.D., M.P.H., Vice-Chairman of the Institute of Medicine Committee and a professor of Pediatrics, as saying: "People should always wear a helmet when they ride a bicycle, and our studies show that when parents wear them, children do too". Also, don't forget reflective clothing when riding at night.