The forecast will be wrong. Make one anyway.

Every forecast is wrong. That is not a reason to skip forecasting. It is the reason to do it properly. The useful questions are not "what will revenue be in 2029". They are "how is this likely to be wrong, which assumption does the damage, and what do we do on the morning it happens".

An honest forecast is a decision tool wearing arithmetic. Building one drags every assumption out into the open: what the price does, how fast customers switch, what the competitor does about it, how long the regulator sits on the paperwork. Once the assumptions are on the page, people can argue with them. That argument is worth more than the number at the bottom of the spreadsheet.

What a good forecast contains

• A band. A single line says "trust me". A band says "here is what I believe and how sure I am", and a board can plan against both edges of it.
• Named drivers. The three or four assumptions doing most of the work, written plainly enough that someone can disagree in the meeting rather than after the money has moved.
• Sensitivities. Which assumption, nudged a little, swings the answer a lot. That is where the diligence hours should go.
• Early warnings. The handful of things to watch in year one that show which future is actually arriving, while there is still time to steer.

What investors actually believe

We build forecasts into fundraising packs and feasibility studies, and the pattern repeats. Investors do not believe hockey sticks. They believe machinery. Show the workings, show the sensitivities, include the bad year, and a cautious number becomes persuasive. A confident line with nothing underneath it persuades nobody.

You forecast so that the bad Tuesday, when it comes, is a scenario you have already rehearsed instead of a fire drill. If reality can surprise you without breaking you, the forecast did its job.