Who is a hero?

I just heard an interview on NPR about Amelia Earhart. The interviewer said she admired Earhart because she went after what she wanted, w/o regard to what other people said. So what, that would apply to all narcissists and sociopaths, including people like Hitler & the church shooter. This debases the meaning of the word "hero", as much as referring to victims of a tragedy like the church shootings as "heroes", and makes it less useful when we want to use it to describe actual heroes.

A hero is someone who voluntarily performs a significant act for the purpose of helping other people, whether directly or indirectly. A person who happens to be in the wrong place at the wrong time and just happens to be struck by a bullet meant for another person, thereby saving that person's life, is not a hero. A person who gives a dime to a poor person is not a hero.

The medical people who went to Africa to help treat Ebola victims, at the risk of their own lives, were heroes.