People are very susceptible to confirmation bias. They see what they want to believe and tend to ignore evidence to the contrary. Read about "street light interference" and be amazed.
... Of course, I have no hard proof, but it seems much more likely to me that it is happening rather than that it is not.
No proof --> fantasy.
That is not a good way of thinking. You are acting like this is some sort of legal case where traders are "innocent until proven guilty." The problem is that this is not a legal case. For instance, if a person gets hired at a store and the customer service reviews of the store happen to go down in the weeks following this, it is reasonable to conclude that the new employee is to blame in some part. Sure, there is no hard proof of this, but you cannot consider the possibility a "fantasy". In fact, it would be ignorant to do so. The same goes with traders and market movements.
I agree. Yes, proving manipulation would be the ideal case, but that doesn't mean we should not be suspicious or at least questioning market movements. Just because manipulation is not plainly clear doesn't mean we should assume all is fine in coinland.
I agree that the possibility is real, though actual occurrences are rare and inconsequential. However, people frequently believe that specific moves in the market are caused by manipulation without any evidence (other than the movement itself), and that is fantasy.
You are right in that specific instances could just be "fantasy" rather than actual planned market manipulation, but I don't think that is what the question was. I don't like the use of the word "fantasy" here by OP as it basically conveys a very black and white picture where market manipulation either is in full effect or does not exist at all. A more correct term would be that it is "possible", if not "probable". It is simply too easy for there to not be some financial party that has been benefiting from planned market movements to increase their wealth, whether this be an individual, an organization, or a fund that is causing it. A wall can be set up by relatively small amounts of bitcoins in the magnitude of hundreds, which considering some people's worth, is definitely achievable.