McCain turned an honorable POW record into a lifelong career. The problem is being a POW isn't really a resume enhancement for taking a job that requires leadership or one where you tell others how to live.
According to the guys who served time in the Hanoi Hilton with McCain, he is not hero. In fact they say he sang like a canary to the Viet Cong to get some special treatment. His canary singing plus being the spoiled son of an Admiral in charge of Pacific Operations made him a favorite with the Viet Cong and Jane Fonda, but not with his cell mates.