If a member of your family suffered a medical emergency, you could certainly call for trained emergency medical responders, but what would you do while you're waiting for them to arrive? Every second counts during a medical emergency.
Recognizing the early signs and symptoms of common medical conditions and providing appropriate treatment can mean a better outcome for the patient and can greatly reduce the seriousness of the illness, which means a shorter hospital stay and lower medical costs. It's also very satisfying to know how to help someone in a time of need.