Also, the main difference here is that Manson and the Son of Sam killer killed simply to kill. The mafia, while an evil organization who ruined countless lives,

Also, the main difference here is that Manson and the Son of Sam killer killed simply to kill. The mafia, while an evil organization who ruined countless lives, actually did employ people and provide services and benefits to actual people. It doesn't excuse their actions at all, but it highlights why some might be able to overlook some of their bloodiness.