JFK was assassinated; that is a fact. Another fact is that the reason(s) for his murder have not been disclosed. It is pretty obvious, that his murder was thoroughly prepared and not the random act of a madman. His assassination remains an unsolved mystery so people continuously speculate by putting forth their own conspiracy theories. So here I come with (partially) my own hypothesis. Nothing similar was mentioned in Oliver Stone's JFK movie, nor in the Warren Commission report, and was never publicly discussed by the mainstream media. But to me, this is the primary motive.
One fact, is that JFK decided to sign Presidential Executive Order 11.110, which permitted the Federal Reserve to issue small denomination bills to replace outgoing silver certificates. Prior to the act, the Fed could only issue Federal Reserve Notes in larger denominations. The purpose of the Order was to facilitate the reduction of certificates in circulation. At the time, the price of silver was higher than the dollar value minted on the coins. It was a reasonable Order, but six months later he was assassinated.
Another fact, is that JFK was actively working on Fed issues and might have had the intention to change something. What if he had become deeply concerned about the Federal Reserve's activities or future strategic plans? What if he had already decided to pass its responsibilities on to a more transparent institution? What if he had understood the ramifications of a future end to the Bretton Woods agreement and its termination's impact on future economies? There were already deregulation plans prepared and the plans' authors were just waiting for the "right" president.
This is a tremendous motive, isn´t it? Moreover, the rulers of the Fed had the power and the resources to prepare the assassination of any American, including the President of the United States. They even had the power to cover up everything, pass new laws through Congress, lock up the Warren Commission's evidence for 50 years, and finally, to carry on with their own plans. Yet another indisputable fact, is that a few years later, after the situation had calmed down, the U.S. unilaterally terminated the Bretton Woods agreement which was the first step towards global deregulation. The Fed even had the power and means to silence his brother, who may have been aware of JFK's intentions. Easy, clear, and simple.
I believe that JFK was murdered because of his ideas. Either the Fed's gluttony was revealed to him, or he had revealed his "fair and transparent institution" ideas to his killers. Historically, "plain-truth-tellers" have always been the victims of assassinations.
This is my final conclusion.