Win rate is only one ingredient
Expected value combines the probability and size of every outcome. In a simplified two-outcome model: expected result = probability of a win × net winning amount − probability of a loss × losing amount. Costs must also be included. A high win rate can coexist with negative expected value.
Consider an illustrative binary contract with a $10 stake and an 80% net payout on a win. A win earns $8 profit and returns the stake; a loss forfeits $10. One win and one loss therefore produce −$2, not zero. This is a hypothetical payout, not an offer or an estimate of future results.
Asymmetric payouts raise the hurdle
With only wins and losses, no fees and a net payout fraction r, the break-even win probability is 1 ÷ (1 + r). At r = 0.80, that is about 55.6%. A true probability above that level would be needed for positive expected value under those assumptions.
Actual payouts may change by asset or time. Refunds, ties, fees, unavailable quotes and settlement rules can change the calculation. A displayed success rate without payout history and a complete record of losses is not enough to evaluate a method. A small historical sample cannot establish its true win probability.
A sequence is not an average
Even a method with positive expected value can have losing streaks. If independent trades each had a 50% loss probability, the probability of losing the next four would be 0.5 to the fourth power, or 6.25%. Real outcomes may be correlated, so independence should not be assumed.
Doubling after a loss does not improve the underlying odds. Starting at $10, stakes of $10, $20, $40 and $80 expose $150 across four losses. With an 80% payout, a doubled next stake does not always recover accumulated losses. Account limits and finite capital eventually stop the sequence.
Choose the boundary before the opportunity
Set a maximum amount you can afford to lose without affecting essentials, debt obligations or emergency savings. Then define a smaller session loss limit and a rule for stopping. Do not borrow to fund speculation. No risk-control rule makes a risky product safe.
In binary options, the full stake is typically at risk; an early exit may be unavailable or discretionary. In leveraged products, gaps and contractual terms can produce different loss profiles. Read the actual agreement rather than importing risk assumptions from another instrument.
Try this on paper
Using imaginary stakes only, calculate the break-even win rate at 70%, 80% and 90% net payouts. Then calculate the result of six wins and four losses with a $10 stake at 80%. The net result is $8 before other costs; explain why changing the payout changes that result.