Everyone who has ever been right about something loud enough to remember it will tell you they called it. The screenshot arrives after the match, after the candle, after the election. And there is no way to know whether it was written on Monday or edited on Friday. This is the quiet rot at the center of most "track records": a prediction you cannot date is not a prediction at all. It is a memory with good lighting.
The technical name for the problem is look-ahead. If a forecast can be created, tweaked, or cherry-picked after the outcome is known, then it carries zero information about skill. The only fix is to make the timing of a prediction independently checkable вАФ to prove a document existed in a specific form before a specific moment, without asking anyone to trust you, your server clock, or your database. That is precisely what OpenTimestamps does, using the Bitcoin blockchain as a shared, tamper-evident clock.
Why timing is the whole game
A forecast is a bet against the future. Its value comes entirely from the fact that the future was unknown when the forecast was fixed. The instant you allow post-hoc editing, every desirable property collapses: calibration becomes meaningless, Brier scores become fiction, and "I predicted this" becomes unfalsifiable.
