When digging in most conspiracies, you could notice that many of them somehow connected to the 70-s of XX century.
For example:
Since 70-s we have no any significant scientific discoveries. I mean really game-changing things. Last one was laser. It was real discovery of something simple but never seen before. Totally new thing, that change nearly everything. We see a lot of game-changing discoveries before 70-s, but none after. Just like progress was intentionally stopped. The only significant progress I could see is in the electronics. And it is just miniaturisation of pre 70-s stuff, not something really new. Even in USSR higly promising ternary computers was dropped exactly in 70-s. As somebody said, "we dreamed about flying cars in XXI century, but got only fucking 140 characters in twitter".
Space exploration. As soon as humanity get a technical ability to explore external worlds, (it does not matter, was moon landing a hoax or not, the important thing that it was technically possible) it was limited to habitable LEO stations, nothing more. In 70-s.
Climate. All that dumb thing with fighting climate change started in 70-s.
Firearms restrictions all over the world, prohibition of psychodelics, changing terrorism from "killing political opponents or high rank authorities" to that strange thing they sold us as "terrorism" now (did you notice that only beneficiars of "terrorism" is governments and never ones who blamed? So what is the point for blamed to repeat something completely useless for them again and again?), etc. All that starts in 70-s.
Just check, you will find connection of nearly every conspiracy to something in 70-s.
It's not only my fantasy. Others find that strange and suspicious too. Look at https://wtfhappenedin1971.com/ or https://www.epi.org/publication/raising-americas-pay/ (just check the "Poverty rate, actual and simulated 1959–2012" graph. It shows that right after 70-s, each time poverty rate drops, it inevitably returns to exact value of 15%. This is definitely an intentional thing.)
So, the root and the key of most conspiracies is in something in 70-s. If we find what happened in 70-s and who is behind, we will get a key to nearly every conspiracy we talk about here.
Any suggestions or may be some more evidence?
The Jewish subversion of US government and culture really went into full swing in the late 60s and early 70s with the frankfurt school, civil rights movement, attacks on the traditional family unit via the sexual revolution and so on, so I think your observation is largely an artifact of that. I'm not a big JFK booster, but I've always seen his assassination as a major turning point for the nation, we stopped being in control of our own government at that point in a way that hadn't been the case prior. The sitting president was killed by elements from within and the coup ultimately went unchallenged. Some people like to go back even further to the creation of the Fed or the civil war or whatever but I agree the 70s were the first real lost decade of America.
One more thing I can recall about US and USSR.
On the edge of 70-s the western stuff invades USSR heavily. "western clothes is cool", "Beatles is freedom", "Money is everything", etc.
But that was not one-direction process. In the same way eastern ideas invades US. When both systems ideologically and systemically became close enough, one was quickly discarded.
Now we all live in some weird mix of socialistic capitalism, or capitalistic socialism idk. Huge private corporations merged with governments, people and small/medium business is a source of wealth for them. There is some social support for the lower class, but not above the level where one could start some real business and get independency.
And a huge growth of bureaucracy in both systems. More restrictions, more regulation, more control agencies, more bureaucrats for each aspect of life. Slowly, but inevitable.
Right now few things that is not easy to repel are under heavy attack. In both US and Russia. Say, first an second amendments in US and free education and worker rights in Russia.
We have a relatively popular conspiracy, that Putin is a direct puppet of US government. As I see Americans have similar conspiracy about "russian influence" on their leaders. ( when you know about both of them, it is very funny to look at that endless loop of accusation. :) ) Both are attempt to slide the attention to "geopolitical enemy" from real masters.
And that global unification of the world was started in 70-s.
JFK was definitely a part of it. Show every politician solid proof that you can have them killed, fabricate an assassin to take the fall for it, then kill him to silence him and settle it and pacify the nation. If people know they can get killed for standing up to you and nobody will do anything about it, lots of people will become more obedient.
This is not US only thing. Scientific progress stopped everywhere in the world. Firearms restrictions also was worldwide. US and USSR being ultimate enemies before made a very strange agreements in numerous spheres, from USSR oil and steel trade to US up to copying US computers in exchange to dropping USSR computer architectures. Even Jewish subversion of USSR government and culture was nearly the same (with local specific, of course). Literally tons of similar changes all over the world. Like somebody tried to unify things everywhere on the planet, even across the worst enemies.