Don't forget that during Castro's take over he threw all American organizied crime out of Cuba, which before Castro was a goldmine for the US mob. The CIA hated the fact that a communist regime was less than 90 miles away from the US. The anti-Castro Cubans hated Castro and wanted their country back. So, they banned together for what would be the Bay of Pigs invasion.

The CIA would train the anti-Castro Cubans for their invasion, and they would also provide critical air support for the anti-Castro Cubans. The mob was happy at the idea of getting Cuba back.

But when the invasion started, JFK pulled the plug on air support from the CIA because he feared an attack on Cuba from the US would cause a bigger problem. The Cubans were slautered, the CIA was humiliated, and the mob was unhappy that they lost Cuba.

That is possible motivation for the mob to help a hit on JFK