They are interesting.
Especially sadists/paraphiliacs, schizos like Gatter/Chase/Mullin/Christopher or politically motivated individuals like Franz Fuchs. Particularly the medieval serial killers were epic and the execution methods they used on them (like with Peter Nirsch).
They’re super interesting, even the most fucked up ones like Ed Gein.
Ed Gein is not the most fucked up one by far. He was just a loner who lost his mind.
For real sick fucks look at:
Frank Gust (sadist/necrophile/zoophile, tortured women to death, was caught before realizing his dream of making a woman pop, tested the equipment on a sheep first)
Bob Berdella (tortured his victims to death over weeks/months, killed one via insertion of different vegetables)
Jack Owen Spillman (pedophile/hebephile/ephebophile sadist with necrophilic/anthropophagic tendencies, very brutal gore images especially here, the baseball bat image will never leave your mind)
Sergey Golovkin (melted faces via flame, let his victims choke to death on gloves, cut off faces/noses/ears, did castration/vivisection/cranial openings, all on little boys while they were alive, he showed the remains then to his next victims, he often tortured multiple boys at the same time and showed them the dissections of their friends)
Randy Kraft (eye lid removal, castration, penetration with socks/own cut-off genitals/sticks, penetrated the urethra with cock tail swizzles, burnings, forcing dirt down the throat) - btw: The Candyman did many of the same things only that he used broken glass for urethra penetration
And David Parker Ray of course - who was a sick sadist (but who isn't a confirmed serial killer), he built a device where women could be raped by dogs and put his victims in gynecological chairs, he also liked to insert electro shockers into their cunts
These were sick fucks that tortured their victims to death in the most fucked up way. Ed Gein was tame compared to that.
Or Richard Trenton Chase - who sucked blood using a cut off dick of a baby as a drinking straw. Or Christman Gniperdoliga who made wind plays out of his rape babies he had with girls he kept in his cave. Or nepiophiles/baby rapists and other disgusting shit. Serial killers are the prove for objective evil and therefore they are far more interesting than mass shooters.