Catastrophizing usually comes in a litany of steps that start from a mundane setback all the way to absolute existential hoplessness. For instance:
1. Oh no, I'm going to be
late for
work.
2. My boss is going to be angry.
3. I'm going to lose my job.
4. I'm not going to be able to get another one.
5. I'm going to be unemployed
forever.
6. My family will starve.
7. Oh God, we're all going to
die!!!
Each step in the sequence is arguably plausible, but the snowball effect takes it into the realms of absurdity after a while.