You needn't take my opinion on board! Just observe that other informed individuals have arrived at that conclusion for good reasons .. It may not be as widespread a thing as is said by some but certainly, at least some influential inventors have been silenced or worse throughout history, having posed a direct threat to the "big monkey" in charge (Need I elaborate?)
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On a discussion forum, opinions are there to be discussed. And when I see some that I think are wrong, I say so. The search for FE cannot be done without searching for truth, at least scientific.
I think the reasons you mention are not. The idea of believing that everything we observe is the result of an intention, of a will, of specific and simple projects of manipulators or exploiters who would like to dominate and shape the world is the basis of conspiracy theories.
Such people exist, of course, and Snowden, whom you mentioned, is one of the useful people who denounce them. But what we observe in the world is, with some exceptions, the result of a multitude of complex causes and effects that no one can control. Assuming simplistic explanations and scapegoats for any event is a refusal to exercise one's intelligence and to do the long work of analysis that is nevertheless indispensable for understanding world events.
The result is that we produce arguments of circumstances, that is to say that we invent one thing or its opposite according to the subject and the intellectual bias of the moment.
For example, one hears that if we do not have FE, it is because there are too many power and financial interests at stake that are opposed to it, inventions would be suppressed, inventors threatened, etc. etc., and not a single brilliant inventor would succeed in making his invention known, not a single brilliant physicist would succeed in making his discovery known, so powerful would be the opposing forces at play.

But why don't we say that a big company which would have a free energy machine and would spread it all over the world, would acquire an enormous power over societies and would obtain financial interests as never before in the history of humanity? We don't say this because we observe that we don't have free energy. So the same reasons with which one would explain that a company would acquire a monopoly and power if it sold free energy are used to explain that it does not sell it and wants to prevent others from selling it. This is all completely arbitrary and inconsistent.
All conspiracy theories invent simplistic causes for complex events or for simple events that have been made complex in order to make them great mysteries that will excite people. The failure of free energy is part of the second case.
Nothing is explained by distorted and oversimplified answers, so that they can be understood even by people with an IQ below 100. But these people are happy to have the impression that they understand what is presented to them as the solution to an intriguing mystery, when they do not understand anything, and they relay everywhere the lies that manipulators (like Putin) or other unintelligent people like them, have produced.
Yet there are far more manipulators around conspiracy theories, than there are in the big companies that want to make money. The free energy movement is particularly affected by this phenomenon. The failure of free energy has a simple but frustrating cause that is therefore rejected: the issue is complex and not yet solved.