Let me try to shine a light from a differant perspective.
I think if a person drives a vehicle long enough they will eventually have an accident, in either a car or a motorcycle.
So I dont think it is as much of a motorcycle issue as it is just the odds of having an accident the longer you drive.
If you ride a motorcycle more than a car, then your chances of having the accident on the motorcycle are greater.
If you drive your car more than your motorcycle (i.e. car main transportation and only ride the motorcycle on weekends or once a month etc) then your accident has higher odds of occuring in your car than your motorcycle.
And since everyone has at least one accident in their life, the severity of your injuries are dependant on what you are in.
getting rear ended in your car can often result in minimal injuries.
The same rear end accident if you are on your motorcycle can more often than not be severe.
So motorycle riders shouldnt get all offended when they are told they will eventially go down because the truth is they will eventually have an accident, either in their care or on the motorcycle. If that accident is on their bike, then more than likely they will "go down"