For instance, if one person leads a pretty level life, doing little good, but also little harm with a baseline of zero.
Another thing is that some people live their life without any form of crisis situations and they look down or make fun of those who have bad days. So it's kind of like comparison is waste. Some of the time comparison is done for the filtering and some of the time comparison is done so that there is some good return of value for the person who does the comparison.
We can never actually know how another feels. It is like the weather - while it is the same temperature, I can be warm, my wife cold - how can we actually know what "being cold" feels like for another? We have to assume that our feelings are the same as theirs in order to empathize. I can eat quite spicy food, my wife can't - are our tongues fundamentally different?