You're not a scientist or an expert, they went to study the issue, several years. Do you think you can replace their knowledge with dramatized books or documentaries?
Can a person be abusive, psychopath, narcissist one or the other or in combination without being a serial killer, probably right? and what is the ratio of people who are one of those or a combination that is not a serial killer?
Is it 1/10, 1/100, 1/1000.. you don't know, because you are not an expert. You can be a serial who has not demonstrated any of those traits, because you can be a high functioning psychopath and people don't know you are one.