Mangano´s bread and butter was gambling. He was a known bookmaker. He had numerous arrests on gambling charges back in the day. He also operated a New York City clothing store, Resource Sales Inc, a store that was formerly operated by Funzi Tieri. In 1981 til 1982, Mangano was behind bars for refusing to testify before a New York federal grand jury. Around this time he was also apparently investigated for corruption in the Dallas based Army Air Force Exchange Service and their links with companies that dealt with them. However, Mangano´s links to these companies are unclear.

Mangano was also known as a heavy gambler and often visited Atlantic City. He was on a "grey list" of 60 to 70 names of individuals and the casinos were told not to extend credit or complimentaries to those people on the list. Once casino officials of the Golden Nugget told an obstnate Mangano when he was in town, that their instructions came from the gaming division. Amazingly, Mangano returned to the casino not long after with a letter from the same gaming division stating it never told the Golden Nugget not to extend credit to Mangano. Two years later however, Mangano was placed on the Black list, banning him from the Atlantic City´s casinos.

At the labor racketeering trial of John DiGilio some surveillance tapes were played. On them, DiGilio spoke about Mangano. He said "Bayonne is mine. Don´t nobody, you know, not anybody, not Benny Mangano...I´m the only tough guy in Bayonne. For years I´ve been chiseling, come to a grand a week." Later on the tapes DiGilio asked "How did Benny wound up in Bayonne? Benny thinks Bayonne is his. That´s the way he spoke take money off my fucking guys and nobody gets nothing." DiGilio was found not guilty in that trial but was found murdered floating in Hackensack River soon after his acquittal.