go watch Mindhunter on netflix.

its a fictionalized story based on the book by one of the guys that pioneered the profiling of serial killers with the FBI - the agents in the story are made up but the killers they present are true.

From stuff I've watched and read it's completely random. Some do it out of boredom, some have a compulsion that is like an itch you can't scratch. A major one that seems to come up a lot is the finality of it. They are basically playing "god." To be able to be a serial killer and not be one off I feel as though you have to be mentally unstable. Most people feel guilty about stealing a candy bar, stealing a life would be a heavy burden to bare unless you aren't all wired correctly.

It depends on a lot on the type of serial killer.

Mission based killers, basically their convinced that taking these lives is adding up to something tangible. To them each kill is the satisfaction you get from success of completing a really hard task that will benefit your life down the line.

Power and Control killers, its not so much taking the life, more that each time they do so they prove to the world their better than the person they just killed. To take a life is the ultimate form of control over another human being.

Visionary killers are usually insane, they honestly believe that either something is commanding them to kill or that the person their after must die for some reason.

Finally hedonistic killers, simply take pleasure out of the act itself. Their most often sexual homicides, but it doesn't need to be. Their generally split into three subcategories: Lust Killers, Thrill Killers and Comfort Killers.

There are other sub categories, but generally those are the four main motivations (their are also cases where the person is simply so far gone they honestly can't stop themselves from killing, but their extremely rare).

However, most of the time it can be boiled down to the idea that they have a hole in themselves. One that they need to fill, and that is usually done by killing.

The twisted thing about serial killers is often the actual killings the point their least interested in. Usually their thrill comes from all the preparation and ritualistic elements that build up to kill.

The thing about that question is you would have to ask one. I'm sure there is someone in jail that would explain it.

I believe it varies depending on the killer, but some say it's a sort of compulsion that either they couldn't or didn't want to resist. There are prob more ppl going round not acting on this type of compulsion tho but obv we only hear about the ones who do & get caught.

Complete control. Playing god. Pinnacle of power.