Like any concept, sacrifice is a word having multiple meanings. If you are the one being sacrificed for some cause, it definitely sucks! On the other hand, when you volunteer to sacrifice one of your possessions (or even yourself) it is more positive. Yet all in all, a sacrifice is not always viewed the same from the standpoint of the one doing it, or those watching them do it. And it is a matter of balance of course: those who have empathy will often sacrifice too much, and end up harming themselves in the process.
It is said that "Givers need to set Boundaries, because Takers won't!" And relationships somehow always need fine-tuning to make sure the levels of give and take balance out. Of course there are still people who give considerably more than they take, and that might cause them problems. So empathic humans need to learn to take care of themselves first because you can't pour from an empty cup.