Being inside the helicopter when things go haywire does not mean that you are OK. Some years ago we had an accident, where Jet Ranger tipped on it`s side during take off. Pilot, wearing a helmet, survived with few bruises, but not so the doctor, sitting next to him. He got fatal head injury by a piece of M/R blade, wich recouchetted back into fuselage. (doctor was not wearing a helmet)
Think about this next time you leave your helmet behind.