Don't feel insulted and don't let it bother you. Actually, this situation is very common. Would you believe that the two groups that I am unable to help are my family and friends? They implicitly trust their doctors, sometimes to their detriment, and they too think I am crazy. Some of them think I am trying to kill them.
So what do you do? Love them, let them go, but keep the door open should one day they need you.