Money certainly gives a happy life and protection to a good extent. We can arrange for ourselves a good standard of life. What we mean by the given statement is having capacity to spend money for curing one's disease, is not always enough to get cured. Just an operation and some medicines will not cure some diseases. There are more things required.
But when we fall ill, we realize this. We want to get alright with in a short time as we do not like to fall ill. But certain diseases cannot be cured easily or in short duration. Many diseases take long durations to subside. During the illness one needs love, affection and close support from close relatives or friends. That care and affection helps in the cure. One needs to be mentally strong. Some times our age or some other disease we have, comes in the way of treatment. There may be shortage of medicines or doctors, especially in rural areas.
One needs a disciplined life during illness and afterwards. Also, the above tells us that we have to be careful in taking care of our health. Being careless can land us in trouble and later one cannot always buy health using money.