Well, in the end, the most fitting phrase is, "Greed kills you." I've also experienced that, even when I first started trading. The mistake was simple: letting a target I'd already reached stay HODL. Holding on as long as possible, I initially thought it would continue to rise. Target 1 was reached, then target 2 was reached, and then the next target's profit didn't meet my expectations. Luckily, it was still profitable, even though it wasn't as big as target 3. There's still something to be grateful for.
I agree with your words.
It's about balancing between greed and fear. Because while greed is destructive, too much fear can also lead to losses and, in some cases, negate the potential profits because you panicked and sold out. You have to balance out greed and fear and I think that is the most important aspect of trading, more than the analytical skills; it comes down to emotions and decision making during tense times.
But in general, I agree that controlling greed is more important than fear because while fear limits your profits, greed takes away everything. I learned that hard lesson when the USTC (Luna) madness happened and I kept holding despite seeing clear signs of an apocalypse.