I don't understand this fascination with Casso. He was a sociopath who happened to be in the Mafia. I personally find the figures who were not purely homicidal maniacs but were capable of restraint to be far more interesting. These individuals are the ones that separate LCN from the Mexican Cartels or the Bloods and Crips and allow them to be romanticized.
Casso was in the mafia, not a social worker. Homicidal maniac is an over used when mafia members are discussed. The vast majority of people they kill or intend to kill are people part of the life, it's not like they are serial killers trolling the streets for innocent people. The fact that he was a huge earner and had his hands in so many different rackets makes him interesting to me. He also had the mafia cops working for him, and was on the FBI's most wanted list for over two years while he still ran the family from the NYC area. Outside of one or two people Casso wasn't killing random citizens like the Bloods & Crips, and the Mexican cartels. He was being fed legit information on rats, and people who weren't showing proper respect to the family. I think any mafia boss or member would have no problem "doing away" with these types.
