IMO - Casso's entire career. After he got the power, the guy was constantly setting up proxies then a proxy to oversee the proxy. This repeatedly resulted in Casso having proxy 2 kill proxy 1.

Fucked over DeCicco & Gotti, D'Arco, Chiodo, Patty Testa, Amuso, "Whack Jersey" not to mention he chiseled that family outta house and home while he was on the lam. The balls on this guy to be in hiding and still heavily lean on the biggest earners in the family to dump hundreds of thousands into reconstruction on his wife's mansion.

The shorter list would be guys he didn't fuck over and it was only because he got pinched before he could have em set up for something. Georgie Neck, Frank Last, and Frank Pagagni are they only people who come to mind and those were his young turks that panned out. Had he not been on the run he surely would've had another wave of young shooters to fuck over these three as well.