As far as them getting a degree in compassion skills, why should they? They're having too much fun making other people's lives as miserable as their own . Have you ever heard of misery loves company? However, sometimes they can also be jealous of other people's lives. Did you know those kind of people also thrive on making pathetic judgments to the people they want to control, because it makes the victim feel vulnerable with low self-esteem so that the ignorant demeaning one feels like they have achieved their control over the victim. And guess what, they can start becoming possessive over their victim, for example they don't like others talking to them without interrupting into the conversation, they constantly watch watch over to see what they are doing, or looking at. They make sure their victim doesn't get close to anyone else but them. They give attitudes to the one who talks to their victim for more than 3 minutes without having a bitter mean expression on their face.
One last thing, those kind of people can also have great leadership skills in being a two face. They just love putting down their victim when they are not around.