it's every man for himself可以翻译成中文里一句很经典的话，就是“人不为己，天诛地灭；大难临头各自飞；每个人都为自己”。

【例句】
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。

It's always been every man for himself in this industry. You can't rely on anyone else to help you get ahead.
在这个行业里，一直都是人不为己，天诛地灭。你不能依靠其他人来帮助你出人头地。