One more point on the mob motive.
JFK violated a most sacred mob rule—betrayal.
They won Illinois for him and he “rewarded” them by attacking their leaders.
Absolutely. Also his father Joe may have told the Mafia bigs that they'd have inside access to JFK and - by extension - RFK. Instead of helping la Cosa Nostra, they did the opposite: go after then hammer and tongs. They wouldn't listen to anyone who tried to warn them off.
"Cut off the head, and the tail dies."