You just booked a great trade. Confidence surges, you feel invincible, and the “house money” feeling whispers press it, you're hot. Counterintuitively, the moment right after a big win is often when you should size down, not up — because your emotional state, not your edge, has just changed.
What a big win does to you
A big win triggers overconfidence, euphoria, and a lowered sense of risk. You start seeing setups that aren't there, widening your standards, and feeling like you can't lose — the exact mindset that produces reckless trades. The “house money” effect makes the new gains feel unreal, so you risk them carelessly, as if losing them wouldn't count. It always counts.
Why down, not up
Your edge didn't just improve — your discipline just got more fragile. Sizing down after a big win protects the gain from your own euphoria and keeps you in the game while the emotional spike passes. This isn't timidity; it's recognizing that the win changed your psychology, not your probabilities. Contrast the legitimate version of pressing — sizing up on confirmed edge over many trades — with the euphoric version, which is just gambling with a good mood.
A big win improves your mood, not your edge — and an improved mood with an unchanged edge is exactly when reckless size shows up. Bank it, breathe, size normal.
The practical move
After a big win: consider locking the day or at least banking most of it, return to normal (or reduced) size for any further trades, and watch for size creep on a hot streak. Let the euphoria drain before you trade big again. The anti-martingale logic says press proven edge, not a single lucky spike — and one big win is a spike, not proof.