Learning more about Psychopaths is never a waste of time. It makes awesome material for a game and is quite useful when role-playing villains. Since Psychopaths are capable of making opportunistic "random" acts of violence, theft and anything that can be advantageous the knowledge is a pro-active self defense.
Someone I argued against which ended up being a cyber stalker and bully 4 months back exhibited all the traits of a Psychopath according to the Hare Psychopathy Checklist. Interestingly, he keeps a blog and anyone who is into philosophy, psychology, or criminology can use come to the same conclusion on their own with their own inquiry. I'm sure I'm not alone in experiencing Psychopaths, as they tend to leave a "wake" of psychological destruction around them.
One of the few things one should be afraid of, is a person who doesn't have the same psychological restraints in harming other people. The material you can dig up about psychopaths in the Internet, in science journals and in crime stories is plenty.
The insight that results from reflecting on one's own behaviors, in light of what defines a Psychopath is priceless. Understanding the differences, and commonalities regular humans have with psychopaths makes for better characterization.
I would recommend to anyone who is as afraid of psychopaths, as any sane person should be, is to read up on: game-theory (BS detection, strategy and tactics etc...), empathy, and learning to be more observant.
Ayn Rand (Bio Shock background story)
In GURPS some disadvantages that result of a mature psychopath is:
Overconfidence (self control-9)
Selfishness (self control-9)
The following findings are for research purposes only, and are not used in clinical diagnosis. These items cover the affective, interpersonal, and behavioral features. Each item is rated on a score from zero to two. The sum total determines the extent of a person's psychopathy.
1. Glibness/superficial charm
2. Grandiose sense of self-worth
3. Pathological lying
5. Lack of remorse or guilt
6. Emotionally shallow
7. Callous/lack of empathy
8. Failure to accept responsibility for own actions
Socially deviant lifestyle
1. Need for stimulation/proneness to boredom
2. Parasitic lifestyle
3. Poor behavioral control
4. Promiscuous sexual behavior
5. Lack of realistic, long-term goals
8. Juvenile delinquency
9. Early behavioral problems
10. Revocation of conditional release
Traits not correlated with either factor
1. Many short-term marital relationships
2. Criminal versatility