Most of us who can create worst case scenarios have little difficulty doing so.
The house keys were not simply misplaced, they were lost. They were not simply lost, they were found by a burglar. And then the burglar got drunk and decided to sell them to a serial killer.
Given half the chance, our imagination becomes a runaway train rolling through a landscape of disasters.
A gentle reminder: What are the real odds of that worst fear coming true? Probably pretty small. Why worry as if it is a near certainty?