Personally, I feel that the most successful gangsters are the ones who avoid the can and get rich after investing their illegal money into legitimate businesses. There is a guy by the name of Antonio Ripepi, died in 2000 at the age of 98. He was one of the most feared and respected Capo's in Pittsburgh and was still getting envelopes through his son in law, John Bazzano Jr. up until the day he died. On top of that, he owned the largest vending machine company in Western Pennsylvania that did over $6 million per year and owned a cement block company that did over $12 million per year. His other son in law was Costenze "Stan" Valenti, former boss of the Rochester family. Ripepi helped the Valenti brothers break off from Pittsburgh to start their own family in Rochester, NY and brokered the deal with Buffalo to allow Rochester to be independent of Buffalo. He was also tied to the Corbi brothers in Baltimore, both guys being made into the Gambino's. Most people have never heard of him, but he amassed a fortune between his legitimate businesses and his illegal gambling and loansharking rackets.

I'm certainly not saying that Ripepi is the "most successful" as I am just providing an example of a gangster who did it the right way, accumulating a net worth of well over $40 million dollars, both his sons are medical doctors, two of his daughters married high ranking mob members and he never went to prison after 78 years in the rackets.