It is a good question but it happened with lot of successful projects in the early days.

I can try to offer a psychological explanation.  It is a known fact from psychological testing that humans perceive a "loss" of a certain fixed cost to be more painful emotionally than the same "gain" in terms of cost.  For example, experiments show that people will expend more efforts to avoid losing a bet of a certain amount than they will in attempting to win the bet for the same amount, and in general have to be offered a higher reward to balance out the potential loss even when the odds are 50/50.  This is called "loss aversion" and if you search that term online you can find out a lot more about it.

I think what we see here is potentially a "reverse loss aversion".   In practice when faced with a project like the Dero Project people see a lot of unknowns and a high potential reward if they "get on board" but also the potential for a loss if they are wrong about "getting on board".  Worse, they fear they will be "scammed" if they get on board and it turns out those fears are right, i.e. "taken for a fool".  The potential loss here is experienced as much more painful than the potential reward for "getting it right", even though the risk/reward ratio is quite low [edit: very low]

Second, a lot of people (though not everyone) see the choice of getting on board or not as a "leap of faith"; they have to have "faith" in the underlying tech or "faith" in the developer team.  In reality this should be a purely rational decision.  You do your research, look at the evidence for the soundness of the project, and make your decision based on your evidence.  This is how George Soros and Warren Buffet made their billions; not by taking "leaps of faith".  But in reality we are emotional creatures and most of us have to see our decisions in emotional terms and experience them that way, too, which makes purely rational decision-making really (really) difficult.

So what happens to those people who see the choice as a "leap of faith" but are not prepared to make that leap, for whatever reason?  Or did make the investment but have a "loss of faith" when they read misinformation or lack of information a certain way and also see prices go down (as they have done recently) but not enough of a loss of faith to simply cut their losses and move on?  Well, some (by no means all, but a small but vocal minority) feel the "closeness" of the painful outcome of making the leap and getting it wrong, and basically express that negative emotional outcome by "FUDDING" the project, that is, by making vocal their fears as a way of offsetting them, of being "right" in at least this way.  No evidence is required for this because evidence (a part of rational decision making) is entirely beside the point.  What matters is vocalising fears and validating them by having others also start vocalising them, without paying much if any attention to evidence.

In case it is not blindingly obvious, I am not endorsing ANY of this.  I am just trying to offer a psychological explanation for a phenomenon a lot of people have been asking about.  It is logical, from this perspective, that a high potential reward, even with low risk, will increase the FUD factor.