@filmfann , if you’re really looking for a serious answer to this, the only plausible conspiracy theory I have heard about JFK’s assassination is this one:
Sam Giancana, then boss of the Chicago mob, had JFK killed in retaliation for what he believed was a broken promise by JFK’s father, Joe Kennedy, who had mob ties from his bootlegger days. Joe K. had elicited the help of the mob in getting JFK elected. They believed this would buy them unprecedented influence in the Federal government, but JFK, particularly through the actions of his brother, Bobby, instead turned on them. The failure at the Bay of Pigs was the last straw. The mob owned Battista, and his ouster from Cuba cost them untold millions in lost revenues.
Oswald was the shooter, one of them, anyway, but when he was caught, a hitter – Jack Ruby – was dispatched to silence him before he could talk. Ruby was a Dallas night club owner with ties to the mob.
This is all done to mandolin music, but there’s not a lot of tinfoil needed.