The title is a bit confusing. It would be better to say "How hard is life in your county?" Obviously counties that rank high will be more expensive and difficult for people of limited means to find housing, etc. A wealthy family could move to a "hard" county and find that their money goes a lot further.
That was my first thought as well. Higher median income usually means higher rent, and higher rent usually means less money to spend on other stuff. Weird algorithm.
Also, I voted for medium. (626 out of 3135)