It'd be nice to see the gangsters' income tax returns, no? Neil Dellacroce declared $10,000 of "legitimate" income on his tax return. That became the basis of the Feds prosecuting him for tax evasion because he lost $100k in Puerto Rican casino. Cost him 5 years in the can.

I'd guess Gambino was the wealthiest, considering the size, strength and spread of his family at its peak, and all the years he stayed at the helm. But the Feds actually documented that Capone brought in $115 million in 1929 (probably worth 10-15x that amount today).