Presuming You Accept That The Kennedy Assassination Was A Conspiracy; Why Did They Do It?

Well, if we assume that the President's assassination was a conspiracy. There can be many hands behind it. Such as Cuban President Fidel Castro due to the rift between America and Cuba at that time, The anti-Castro Cuban Community - so that they can get rid of Fidel, President Johnson etc. It could also be a mere work of the mafia simply to create unrest and fear. The soviet Block was also very active at that time and there is a possibility that they were involved.

I was once involved with a fellow who was 'connected' as they say.  He told me (and his grandmother told me separately) that his father was involved in Kennedy's assassination.  I do know for a fact that the father was then assassinated along with HIS father, the grandfather.  Now this grandfather was not the husband of the grandmother, who was his mother's mom.  I know it's sounds crazy, but I'd believed in the conspiracy before that, and I have no doubts that it did happen.  Yet the reason is still a mystery to me.  I didn't ask many questions because I felt it more prudent not to.