One of the cognitive distortions identified by cognitive-behavioral therapists is catastrophizing - the tendency to worry about something uncertain, and then immediately update toward believing that the worst possible outcome is true. Rumination - an involuntary replaying of social memories viewed through a harshly self-critical filter - reliably produces worries for the mind to turn into catastrophes.
At first glance, catastrophizing seems silly and self-defeating. The catastrophes predicted rarely come to pass. So why do brains continue to do this even after years of evidence of their own poor predictive powers? Why would a person tend to instantly and without evidence believe the worst, over and over again?
It is my hypothesis that catastrophizing is a completely rational behavior when viewed from the perspective of a self involuntarily trapped in a mind, attempting to minimize pain inflicted on it by the mind. It is a literal "mind hack" - gaming the emotional and cognitive system, rather than meeting opponents in the external world.
First, the self obtains information about the pain-delivering algorithm of the mind. A major feature of this algorithm, descriptively speaking, is that the worst pain is generally delivered in response to a loss - a loss in resources, perhaps, but more importantly a loss of social status or social belonging. A change in social status or other resources appears to matter much more to the pain-delivery algorithm than absolute levels of either. The mind rewards the self when the level of external resources or social status increases, punishes the self when it falls, and does not do much when it is stable. Another major feature is that a loss has much more impact than an equivalent gain, in absolute terms. The self's best strategy is to minimize the likelihood of loss in the future, and it is motivated to do so by rumination and fear.
However, the self has another option to avoid being punished by the mind for losses over which it has limited or no control: the self can manipulate its own beliefs to avoid perceiving a loss as a loss. It accomplishes this by catastrophizing.
When the self catastrophizes, it updates toward believing that a loss has already happened. Since this epistemic manipulation is, first, imaginary, and second, under one's own control, the ordinary pain response to loss is not engaged. Meanwhile, one's internally-tracked "position" is made less precarious and vulnerable to uncontrollable factors; instead of risking a fall from a tightrope, one climbs down to the bottom by catastrophizing.
Should the catastrophe materialize, the self will not be punished by the mind (as much), since it did not subjectively experience a loss - it experienced the world being the same as it predicted. More commonly, should the catastrophe fail to materialize, the self will experience a reward, since from the self's perspective, its position just went from rock bottom to much improved.
In summary, catastrophizing is a strategy the self employs in order to "game" the reward and punishment system of the mind - in a manner that is likely totally at odds with the genetic interests of the organism hosting the self. Rumination, fear, and the infliction by the mind of intolerable levels of pain or shame are likely predictors of the catastrophizing "mind hack."