everyone must take care of themselves and their own interests and safety
This expression has been used since medieval times, but from the mid 16th century onwards it has often been expanded to every man for himself and the devil take the hindmost or, less commonly, every man for himself and God for us all.
1997 - Daniel Quinn - Mylshmael - Tribes survive by sticking together at all costs, and when it's every man for himself, the tribe ceases to be a tribe.
RELATED IDIOMS :
every last = every single
used to emphasize every member of a group
1991 - Colin Dexter - The Jewel That Was Ours – One clue unfinished in a Listener puzzle and he would strain the capacity of every last brain cell to bursting point until he had solved it.