Big money is made when markets fluctuate and when you have better information than other investors. What better way to game the system than to cause the fluctuations yourself?
Now you might argue that such a conspiracy would have to involve so many people that it would be impossible to keep it a secret. I'm not so sure about that. First, you would only need to succeed in manipulating the media 55% of the time, just to pick an example number, and that would be enough to reap huge profits over the long run. And there could still be plenty of dissenting voices and competing points of view, so the manipulation could get lost in the noise.
The key to making the manipulation work is making the manufactured crises more compelling or more "sticky" than the plain vanilla stories that are competing for attention. For example, the story about the shopper stampede only needed to be picked up by one influential news source in order to be copied by all. It could as easily been ignored.
And the stampede story is "sticky" because I will probably remember it for the rest of my life, whereas I won't remember a report of some particular store having lower sales this season. It's the same process used by trial lawyers when they argue their cases in terms of human suffering to have a larger impact on the jury.
It wouldn't require the involvement of many people to control the source of economic statistics. At some point in the process of tabulating the results I assume there is literally one person who sees the total before anyone else. Hypothetically, the "story" of brisk retail sales for Black Friday and shopper stampedes might involve only a few paid conspirators beyond the inner circle of the puppet masters.
I don't actually believe the theory I just described. At least not yet. But if your comments tell me the stores you visited in the past week were empty too, I might revisit that position.