In 1980, scientists proposed a hypothesis that suggested that a meteorite struck earth and caused the mass extinction that included the dinosaurs. why are new hypotheses often criticized?

The new hypotheses proposed by different scientists are often criticized by the others because these new hypotheses contradict the ideas and hypotheses that already exist. Adapting one's mind to a new hypotheses explaining a past event is often difficult when more clear hypotheses were already given earlier. Thus, the hypotheses suggesting the extinction of the dinosaurs are difficult for the scientific community to accept.