In the early years of my account, I fell into a subtle trap: I assumed that if my position size remained the same, the risk would stay the same. With small capital, a few days of fluctuation in a single position didn't cause much emotional turmoil. Later, as my account grew, I continued using the same proportions, thinking I wasn't being reckless. But a single normal drawdown could wipe out enough losses to disrupt my sleep. When you don't sleep well, your trading becomes distorted. You'll find yourself watching the market more constantly, wanting to exit at the slightest rebound and unable to resist adding to your position on every pullback. You talk about long-term gains, but your actions are all short-term reactions. It's not that your logic suddenly failed; it's that the absolute amount of your position exceeded your psychological tolerance. I later realized this: the proportion is risk control on paper, but your feeling is risk control in execution. Your ability to withstand risk isn't just about what percentage of your account it represents, but also whether the fluctuation, when realized in reality, causes anxiety, affects your work, or forces you to act when you shouldn't. A larger account doesn't mean you can scale every trade proportionally. Experience, emotions, and liquidity don't upgrade with the numbers. Slow down when necessary, keeping individual losses within a range you can calmly review. This prevents a single market fluctuation from dictating all subsequent decisions. The truly suitable position size for you isn't the one that looks like that of an expert, but rather the one that allows you to continue following the rules even after a loss. Maintaining composure and a stable mindset are key to preserving your capital over time.