JFK was the 1st US president to really challenge the globalist secret society aristocracy that emerged from the ashes of WW2, which include elements of the military industrialists wedded with the Bilderbergs and Rockefeller , with a lineage dating back to the Rothschilds.
Eisenhower recognized the threat and acknowledged it in his farewell speech, which is probably fortunate since had he been more resistant and outspoken to the threat early in his presidency, he likely would have been assassinated and the coup of USA accomplished earlier.
Truman probably recognized the threat but underestimated it , thus playing into the hands of it by creating the CIA, an act which Truman would latter say was a mistake soon after the assassination of JFK.
Except for LBJ, and Joe Biden, all the other US presidents since JFK have had some sort of assassination threat/attempt occur during their term of office.
Except for Donald Trump, all the other US presidents since the JFK assassination have been very reluctant to say anything critical of CIA, NSA and FBI, probably because of fear of being removed by “any means necessary” as the former CIA director Brennan once suggested as a method to removing Trump from office.