The biggest asset that any individual has in life is his ability to earn an income. While homes and cars are expensive items, they cannot compare if you consider the amount of money you earn in your life.
Medical aid is a programme that allows an individual to protect himself and his family from the adverse ramifications of hospitalisation. This works in two ways. The first is that an individual with medical aid would not have to pay for the costs of hospitalisation and similar treatments.
Falling sick or getting injured in an accident can mean that you would be hospitalised which would result in you not receiving your income for the period in question.
A situation where you become hospitalised because of some unforeseeable incident would not only cause your future finances to suffer but also affect your current finances because of the cost you incur due to your medical treatment.