I think Charles Manson is to some degree a media creation in the sense that while what he had done was horrible I don't put him anywhere near in the same level as Dahmer, Gasey, Bundy etc. I think his murders get over sensationalized because of the 1960's era, location and high profile actress and director involved.
In the end here is a guy who, from the age of 9 to 80 years old has been locked up or institutionalized for all but a handful of years and basically got caught up in a bad situation with a ton of drugs and delusional kids who wanted to impress him.