If an estimate says 70%, it also says 30% to lose. The 30% is not an error. It is part of the forecast and it will show up.
A loss is almost certain across a series
For every tip in a day to win, each one has to win. At 70% per tip, the chance of at least one loss in N tips is 1 − 0.7^N.
How many losses are normal
In 100 tips at 70% you expect 30 losses. The standard deviation is √(100 × 0.7 × 0.3) ≈ 4.6. So a range of roughly 25 to 35 losses is ordinary, and a value slightly outside it does not prove the model broke.
Losing runs worry people more. A rough estimate for the longest losing run in 100 bets with a 30% loss chance is three to four in a row, and five or six is not rare. It does not mean anything changed.
What changes in practice
- One month of results says little. A small sample can swing either way.
- Profit does not move in a straight line. A sound system has losing stretches and your bankrolli has to survive them.
- Raising the stake after losses fixes nothing. Each bet has the same probability whatever came before.
The last point is the gambler's fallacy: the idea that a win is "due" after losses. Matches do not remember your slip.