People also fail in trading because besides «buy low sell high» they dont know anything. When the price goes lower than the original price they have bought for, their plans gets destroyed, because they dont know what to do, that is not what they expected. People like that sell at any price they can, quit and raise panic at the market, thereby creating new wave of unsuccessful traders.
You only loop this together without having that constructive argument about it. There is nothing wrong with traders selling at a high level and buying at a low level as long as they know what they are doing and do not subject it to guesswork or gambling. Such must ascertain the levels through support and resistance levels and also with good analysis to truly know the exhaustive condition of the market which is called overbought and oversold condition.
However, this strategy is good for the long-term approach but the short-term traders can still take advantage of it but would be on the lower timeframe. And for those who experienced the market going against what they planned, I can only encourage them to manage their trading properly, there are no perfect traders and analysis/signal, anyone can fail, and at times, closing the trade at a bad price is good to save such trader from more losses. This is more heroic than the way you made it look bad.
All that matters is to make more wins, but thinking traders will not lose is a pure lie, and in losses, we should not still mock anyone. Generally, to avoid losses, I can only encourage traders to work more on their trading management and psychology. With good strategy as well, I don't think any issue would arise.