Sorry but I disagree. Every man for himself is bad for survival in a few ways.
1) No advantage in numbers during attacks.
2) Those who aren't with you, might have to be against you.
3) It is extremely difficult to survive on your own or in tiny groups. Small communities of 30-50 people would have a greater chance of long term survival as there will be others who have the skills you don't.
Sure - working towards a community poses its own problems... but so does being alone in a vast, hostile world.