Those over in DUmmie Land,OTOH,are convinced...and will always be convinced...that the CIA did it to prevent JKF from carrying out his plan to withdraw from Vietnam.
They overlook the fact that JFK was a cold war warrior to the max.
Was Castro prepared to do business with the mafia? They lost a lot of investment when he took over, maybe they were thinking they could make a deal with him and get back into Havana and other rackets with the communists, who needed money for their military and other ambitions....
Except Kennedy's vendetta aginst Castro made Kennedy an impediment to both the mob and Castro. "The enemy of my enemy is my friend".
JFK did have a long running affair with the mistress of a mafia boss....so obviously the mob was intersted in accessing Kennedy's inner decisionmaking circle.