Anastasia was the don from '51 to '57. From what I have read, he handed out membership for a hefty price of around $40k. That could have been a reason for the large recruitment, as he stood to make millions. But the rumor of charging fees came from Genovese, who was trying to justify the whacking of Anastasia. So, who knows...

Is Carl Sifakis considered a reputable source? According to his Mafia Encyclopedia, under Carlo Gambino's leadership, "the relatively small Mangano operation became the biggest in New York and the nation." In addition, he wrote "Carlo Gambino took a second string crime family and built it into the Mafia's jewel in the crown, far more wealthy than even the family originally ruled by Lucky Luciano..."