I argue that their fucked up pasts gave them an opportunity to see the world from a different perspective but they weren't quite able to handle such mental freedom and they instead became slaves of the system.
Gacy In a nutshell: "I was tied to a radiator and raped repeatedly as a kid and, unfortuneatrly, that imprinted me with fucked sexual proclivity that I acted on as an adult sexualized by NAMBLA. And I now have to feed it instead of doing the world a favor and killing my warped ass".
If only he lived in later times, internet vigilantes coulda put a bullet in him.
People like Gacy make me glad i was only pinned down by my back (Grandfather) and smacked in the back of the head while I slept like Butters. Violent abuse warps less than the sexual kind, IMO. And luckily the sonofabitch died when I was 8.