Saying the points are earned isn't quite right. The points are actually just given. Whether you earned them or not is a different matter. The more points/time/posts the giver has the more points he gives. The value of negative rep is 50% of the givers positive rep power.
If you click on Community > Members List > Reputation you can see the top point whores. Here's a
list of ill favored contributors that have chosen this site to be d!cks on. They are usually the more interesting posters because they invariably cause a sh!t storm of one kind or another and drive the membership crazy.