Many people's trading problems are actually quite simple: they want to catch everything. They don't want to miss any small fluctuations, but as a result, they end up not capturing the real profit-making move. The more they try to eat everything, the more likely they end up with nothing at all.

A more common mistake is the second one: immediately reversing after a stop-loss, changing direction as soon as the trend shifts. A week's worth of market fluctuations can completely overturn the original higher-level judgment. But in reality, short-term volatility is never enough to negate a higher-cycle logic.
Many big opportunities are not something you can hold onto with a single entry; you need to try in batches, tolerate one or two mistakes, to lock in the truly asymmetric position. This itself is a cost.
Most people don't see it wrong; they just can't hold on. They waver amid noise, mistake volatility for signals, and see retracements as logical failures, ultimately invalidating the original correct direction themselves.
To put it simply, the problem isn't entering early, but lacking enough resolve and discipline to stick to a reasonable plan.
Remember one thing: as long as the core logic isn't structurally broken, most of the fluctuations are noise, not a reason to reverse.