It's every man for himself 大难临头各自飞；每个人都是为自己；人不为己，天诛地灭

【例句】
Where I come from, it's every man for himself.
在我的国家，人人都是自己照顾自己。

It might be a civilized place to shop at other times, but come the January sales, it's every man for himself.
人们在购物时通常都能保持风度，但一月大减价例外，这个时候，人不为己，天诛地灭。