What overarching idea is gladwell establishing in his introduction?

The overarching idea Gladwell is establishing in his introduction to the book (Outliers: The story of Success) is that community can make a great impact on a person’s life.

The story is about the town of Roseto, Pennsylvania. Doctors amazed with the low occurrence of heart disease in their community. The inhabitants lived long lives instead of their obesity. The doctors performed many tests, but couldn’t figure out what is the reason.

When they looked at the social structure of Roseto, they see many of the residents would stop to chat with neighbors. It seems that it was the sense of community and togetherness that made them live happy, long lives. So the community can make a great impact on a person’s life.