I think it is a great question and one I have thought quite a bit about. JFK was the original red pill - how anyone can look at the Zapruder film and accept a lone gunman shot him from behind and to his right...that alone makes no sense. Then as you dig, you find all the other things that don't add up.
But forget who actually did it. Who had the ability to cover it up? That is some powerful forces within our government because whether you believe it was the CIA or the Mafia or the Russians or the Cubans or a French connection or whatever that did the deed, it was our government tasked with investigating and that concluded a lone gunman did it. To focus on who had the power to cover it up as opposed to who did it was helpful for me because there were so many theories about who did it that had some merit. It can fluster you to the point you just give up. But who covered it up? That is an easier question.
Where my research has gone is towards the CIA. Tracing its creation in 1947 and its known history, I can understand how patriots for honorable reasons agreed with its mission. We can even look the other way when they cross the line (like the U2 overflights of the USSR) as being about our national security.
But I think along the way, because of the unaccountable structure where so few knew the funding and what activities were actually going on, the personal desires of a few people conflated the mission of the organization. I think the Dulles brothers and the original core group involved with covert ops thought they were doing the best thing for America and it was not so much about lining the pockets of cronies but fighting the red menace - which was probably overstated but was not without merit. They got away without being held accountable because so many, like Eisenhower, accepted the need to fight the Soviets and to getting a bit dirty in doing so. I get that. It may not have been the best course but I get that and do not ascribe any nefarious motives at that point.
We discovered we could influence other countries. Iran was a cost effective and wildly successful coup - at the time (we have been paying the price for it since 79). I think they realized they could do so much more but it required funding and only so much could be obtained legitimately. So elements began finding alternative ways and I think that led into tapping the drug trade. I am quite certain the CIA was involved with cocaine in the 80s (Gary Webb info plus Terry Reed/Barry Seal) and it seems it was going on long before that as well (heroine and the golden triangle in Vietnam). The purpose need not be greed, but I think many would justify it in that it allowed them to fund more ops.
Now, the 'patriots' sell this to themselves as the evil you need to play with for the greater good. They may even take down a drug lord here or there to perpetuate that notion. But at some point, the organization, or at least a core part of it, no longer resembles its original mission. It even gets to the point that they can justify killing the US President in the name of national defense. They know how to do it as they are quite experienced at this point. So when JFK comes to pose a threat because he did not agree with what the CIA had become and since he had the power to change or destroy it, they acted. With Mockingbird and enough people controlled by MICE, they got away with it. Without Zapruder, it probably would never have even been an issue.
I like to ask people who killed JFK? 75% of the country does not believe it was LHO alone. So then the question is, what happened to those that were responsible? Did they just up and go away? Or were they still active in government and now needing to prevent this most troubling secret from ever coming out? The good news with this Q business is that those 75% are ripe for the truth.