Sunk Cost Fallacy

The sunk cost fallacy occurs when past, irrecoverable costs influence future decisions — even though rational economics states that only future costs and benefits should drive choices. The term "sunk cost" refers to any cost already incurred and unrecoverable, regardless of future action. A logical decision-maker ignores sunk costs; a human being almost universally does not.

Classic non-trading examples: continuing to watch a terrible film because you paid for the ticket; staying in a failing business because of money already invested; finishing a bad meal because you paid for it. In each case, the original expenditure is sunk — it cannot be recovered — yet it shapes the decision about what to do next.

In economics, sunk costs are irrelevant to optimal decision-making. In human psychology, they are powerful and persistent drivers of sub-optimal behaviour.

The sunk cost fallacy manifests in binary options with particular force because losses are immediate and definitive. There's no "unrealised loss" that could theoretically recover — each expiry settles the trade absolutely. This makes the psychological pressure to "get it back" acute and immediate.

The classic binary sunk-cost pattern: you lose $200 during a session. Rationally, those $200 are gone — they cannot affect the next trade's probability of winning. But emotionally, they feel like a debt that must be repaid. This drives extended sessions, larger positions, and deviation from the trading plan — all of which typically make the total loss worse, not better.

The key reframe: each binary trade is a new business decision. The question is not "how do I recover my $200?" but "does this specific setup have positive expected value based on my documented win rate?" The $200 loss is irrelevant to this calculation. If you wouldn't place this trade in a flat P&L session, you shouldn't place it in a losing session either.