Answer :
because they probably want to still live the moder day world than this new world my best guess
Some might live there because they have heritage there, as in their family has lived there for generations, and they don't want to give that up. Others might be there because they have no other place to go, and they don't have the money or the experience to go anywhere else. Others may have ties to the community, or they might even have negative associations with those living elsewhere and wish to avoid being in other, far worse circumstances.