I don’t like to make generalizations about conspiracy theories because sometimes the turn out to be true.
Collusion happens all the time and it need not happen at a grand scale.
Even grand conspiracies occur all the time depending on how we define a conspiracy. For example, political parties can be considered conspiracies. I would also consider the recent French taxi war against Uber to be a conspiracy.
All of this is made possible because, rather than throwing out a buzzword to evoke an emotional response, I for one clearly define my terms and proceed in logical steps. A conspiracy is nothing more or less than a group of people acting to achieve an immoral or illegal end.
A related idea is the idea of organic unity. Organic unity occurs when people coordinate indirectly, perhaps due to spurious or lurking variables rather than direct communication, premeditation, or intention. For example, if two people have the same ideology and are exposed to the same information they may engage in similar, complimentary, or coordinated action even without previously communicating with one another.
I’d also add that plenty, I think even a majority, of conspiracies are absurd, but the absurdity of particular theories shouldn’t amount to an attack on theory in general. In fact, even if only 1% of conspiracy theories turn out to be accurate the phenomenon of conspiracy theory in general may be valuable and desirable on the whole from a socioeconomic point of view.
Social networks are things and quite often people do bad things in groups, even if it is less occasionally noticed.