We use mental shortcuts when judging how likely or frequently an event will happen, because we tend to remember our most recent experience and therefore we put more value on that information. This affects people when they are thinking about how likely something is to reoccur. If a recent event produced strong emotions in us, we’re more likely to think this event will happen again.
Citation: Tversky, A., & Kahneman, D. (1973). Availability: A heuristic for judging frequency and probability. Cognitive Psychology, 5(2), 207-232.