$IWF .... Hmmm, those are pretty impressive historical returns.

You have 100 dollars and you want 200. Betting red one dollar at a time, your chance is one in 33,171. Betting the whole 100 on a single spin, it is 47.4 percent. The careful version is fifteen thousand times worse. This is also the arithmetic of your trading account, and it means almost everything you have been taught about managing risk is, in the strict mathematical sense, a method for losing more reliably. An MIT professor works this out on a blackboard in a lecture on random walks. The result is called gambler's ruin. Two and a half points of disadvantage is nothing on one spin. But a dollar at a time you are not making one spin, you are making hundreds, and the edge gets a fresh attempt at you on every one of them. It was never the size of the disadvantage. It is the number of times you agree to face it. One hundred on red, once: 47.4 percent. Twenty dollar bets: 37.3 percent. Five dollar bets: 11.1 percent. One dollar bets: 0.003 percent. Mathematicians call the right answer bold play. It was proved optimal for unfavourable games in 1965. It is not a strategy for winning. It is the least ruinous way to play a game you should not be in. If your edge after spread and fees is negative, and for most active retail accounts it is, then your position sizing rule is not protecting you. Risking one percent per trade is the one dollar bet. It arrives at zero with near certainty, just politely, over a longer period, with a spreadsheet. Discipline does not beat a negative edge. It schedules it. All of this reverses if you have a real edge. Then small and frequent is correct and bold play is madness. So the only question that has ever mattered is whether you have one, and the number of people certain they do has never resembled the number who do. Your broker does not need you to be wrong. It needs you to be frequent.