人不为己？

小时候，记得人们试图批判： 人不为己，天诛地灭！！提倡人人为我，我为人人。Or,  为人民服务。。
这可能吗？ 儿子6 岁，可小心眼不少。 平时跟他老爸玩，他老爸不让他，他输了。
他就会跑来告账： Daddy is bad.
我答：what did he do?
儿子,    he is not easy on me!! He does not let me win!!! 
我答： What can I do?  
儿子：  I hate him. 
我答：  I hate him too.  What can we do?  Lets kick him out!! 
儿子:      No, no, no, I do not want to kick him out!
我答：   Why not?   You dont like him. 
儿子:      Yeah, but I do not want to kick him out, because, at least he can go to work, he makes money for us .               Otherwise you have to work.... I do not want you to work..... you stay home and you can take care of me.

你看：这仫一个小东西，处处想的是自己？ 这难道不是应念了：人不为己，天诛地灭， 吗？