Outsiders are people who don't live in organized cities. They have to worry about the fluctuating atmosphere, the lack of food, and unsafe buildings.
Some Outsiders' areas survived The Ending well, but most did not.
From the mini-strip about Annie the blob, we learn that there are four different areas where Outsiders come from: a stable area, not-so-stable area, unstable area, and miracle area. Each is progressively worse. Stable areas have many survivors, whereas, in the miracle area, there is only one survivor.
Inside of LiFe, Outsiders can explore, connect with others, and earn money.