We all tend to think in a linear fashion, its human nature. That if things have been moving along at a fairly regularly clip they should continue on that trajectory in the future, all other things being equal. If your earnings or cost have been trending at some given rate for the past several years, most people would assume that they will continue at a similar pace in the near future, unless you have a good reason to expect something different to happen. This might include opening a new office, entering a new line of business, an increase in payroll tax rates, changes in staff, signing a new lease, etc. With these items factored in, one could do a reasonable projection.

Then there are dislocations to normal expectations, if radical enough they are known as an inflection points that can change everything almost overnight as they are unanticipated. This can caused a severe disruptions or upheaval in business and personal lives to whatever was considered normal. The cause of this can be due to a change in government policies and institutions, terrorism, a cyberwar, civil unrest, climate change, mass migration, an unexpected death of a key person, etc. Remember the banking crisis as we had a decade ago, the high tech Y2K/dot com bust two decades ago, or the S&L crisis three decades ago. And there are natural disaster like hurricanes, floods huge forest fires, famine or pandemics.