My brother is one of those guys. He has had some respiratory illness for weeks now and won't see a doctor because "doctors can't help. There is no cure for a cold, so what's a doctor going to do?" Well, after weeks of hacking and sniffling, it's possible what he has is not a cold. Only a physician can make an accurate diagnosis. Secondly, whatever is ailing him might actually be successfully treated with medication. Lastly, if what he has is far more serious than a cold, he could be in a life-threatening situation. He is 66 years old and has had one heart attack. If he has the flu or pneumonia he is at significant risk of another heart attack.
But there is no talking to him. He is supposed to see his cardiologist twice a year, but he tries to put off making an appointment for as long as possible. The only reason he does eventually see the cardiologist is to be sure he can continue to get prescriptions for his meds. He's now talking about not taking his meds because he feels fine. That way, he won't have to see the cardiologist.