Imagining the future is necessarily an exercise in counterfactual thinking, which is in any case an extremely well-developed cognitive skill of our species. The trouble with counterfactuals is that they're both absolutely beneficial to our survival, and incredibly tricky to do with any amount of fidelity.

Instead, counterfactuals are most likely mediated by a sort of "primary cause bias." That is, we tend to prefer to perceive events as being driven primarily by significant and singular events. Just think about history: the Stamp Act and similar abuses caused the Revolutionary War, maritime abuses caused the War of 1812, slavery caused the Civil War, a stock asset bubble caused the Great Crash.

So I suspect that the linked phenomenon is the same thing. It's the little things that make life, but we're not really capable of meaningfully conceptualizing that. So instead we look at counterfactuals and try to think about the big things: will I get that promotion, will I have children, will I buy the next more expensive car, will my 401k tank?