I understand your confusion. Perhaps the sentence reflects part of the North American culture. It is written from the parent's point of view. The parents "sacrifice" or "give up" time they would have with their child. They would miss the daily closeness and association with their child. This would be a "sacrifice" for them. For the child, however, working hard at school would be a sacrifice "to" or "for" the parents. The efforts at school would yield a higher paying job that would enable him/her to help support the family. Hope this explanation helps

Naomi is correct; any native speaker would interpret this speech as focusing on the pain the parents feel making the sacrifice. I think the issue is that the preposition FOR has a long list of meanings in English, and you are thinking of FOR as meaning "on behalf of." One could say "parents often sacrifice for/on behalf of their children," but that is not what the speaker means. The speaker is using FOR in the sense of "in relation to or with regard to" the parents here. Other similar uses of FOR in English sentences: This soup is too hot for me. The football players are tired; it was an exhausting match for them. The speaker could even have said this (but probably would not have because it does not sound very good): "The sacrifice your parents made for you was hard for them." FOR is a very tricky word in English! I don't blame you at all for being confused.