Ship Size vs Wave Size

This chapter I will tell a true story — about a friend of mine named "Boy."

Boy started trading with a 200,000-baht portfolio. The first month he made 30% profit. Everyone called him a "genius," including Boy himself. He started showing off in the Line group. Watching, I warned him: "Careful — you did not make 30% because you are good; you made 30% because you used heavy leverage and got lucky."

Boy did not listen.

In month 3, Boy found the trade that "looked the surest of his life" — Gold was about to surge because the Fed raised rates. I said "do not risk more than 1%." Boy replied "this one cannot miss, I am going in with 30% of the portfolio."

The result: Gold ran 80 pips against him within 2 hours.

Boy lost 180,000 baht out of 260,000 in 2 hours = portfolio left at 80,000 baht.

Worse — he could not cut, because he could not accept that he had read it wrong. He held on hoping price would come back; price kept falling. Boy closed at a -200 pip stop → portfolio left at 30,000 baht.

Within a single trade — Boy lost the portfolio he had built over 6 months. From a 30% first-month profit → within 2 hours, 88% of the portfolio was gone.

It has been 3 years now and Boy has never come back to trading.

Boy's lesson — and the lesson of every trader who left like him — is one thing: Position Size.

In treasure-hunt terms — Boy was a captain who "saw the treasure island clearly," so he took the biggest ship + the whole crew + all the supplies → one storm hit → the whole ship sank.

A wise captain does the opposite — "It does not matter how much treasure the island has — what matters is, if the ship sinks, how many ships do I lose."

Here are the 3 Risk-first principles every pro uses:

Rule 1 — Position Size is a function of the Stop Loss, not of confidence

Beginner: "This one looks soooo good — go in big!"

Pro: "Risk 1% of the portfolio = $100, SL is 50 pips away → position size = $100 ÷ 50 pips ÷ pip value = the right lot size."

The feeling of "confidence" has nothing to do with this calculation — because the trade you feel most confident about is the most dangerous trade (as Boy proved).

Rule 2 — the 1% rule (or 0.5% if you are starting out)

Never lose more than 1% of the portfolio on one trade — no matter how confident you are.

- Lose 1% for 10 trades in a row = portfolio at ~90% → need +11% to recover (2-3 months) - Lose 5% for 10 trades in a row = portfolio at ~60% → need +67% to recover (1-2 years!) - Lose 10% for 10 trades in a row = portfolio at ~35% → need +186% to recover (almost impossible)

This is the asymmetry of loss — you lose fast but recover slowly.

Rule 3 — Risk:Reward at least 1:1.5

Do not enter a trade that risks $100 to make $100 — after commission + spread + slippage you would need to win over 55% just to break even.

If R:R = 1:2 → a win rate of just 40% still profits. If R:R = 1:3 → a win rate of just 30% still profits.

This is why pros reject most trades — they wait only for the ones with a genuinely good R:R.

The most important thing in this chapter: you do not control the market — you control only your position size and your stop loss. These two are the only wall between you and becoming Boy.