I doubt if all serial killers have the same reason for killing their victims, there are several reasons why people who kill others do so. Some serial killers kill because they were victims of child abuse when they were quite young and defenseless, so they grew up feeling angry at the society and everyone for not being able to protect them. Some kill because of their love for money, while others do it simply because they derive pleasure from it, but there are several other reasons why serial killers never stop killing people.