This paper tests the effects of lay beliefs that disaster victims who have been victimised by other events in the past will cope better with a new adverse event than first‐time victims. It is shown that believing that disaster victims can get habituated to suffering reduces helping intentions towards victims of repeated adversity, because repeatedly victimised victims are perceived to be less traumatised by a new adverse event. In other words, those who buy into habituation beliefs will impute less trauma and suffering to repeated victims compared to first‐time victims, and they will therefore feel less inclined to help those repeatedly victimised victims. This was demonstrated in a series of six studies, two of which were preregistered (total N = 1010). Studies 1, 2, and 3 showed that beliefs that disaster victims become habituated to pain do indeed exist among lay people. Such beliefs are factually inaccurate, because repeated exposure to severe adversity makes it harder, not easier, for disaster victims to cope with a new negative event. Therefore, we call this belief the ‘habituation fallacy’. Studies 2, 3, and 4 demonstrated an indirect negative effect of a belief in the ‘habituation fallacy’ on ‘helping intentions’, via lesser ‘trauma’ ascribed to victims who had previously been victimised. Studies 5 and 6 demonstrated that a belief in the ‘habituation fallacy’ causally affects trauma ascribed to, and helping intentions towards, repeatedly victimised victims, but not first‐time victims. The habituation fallacy can potentially explain reluctance to donate to humanitarian causes in those geographical areas that frequently fall prey to disasters.