Assuming that you agree, not knowing which way the market price action really goes, depending on fundamental news, economic data and interpreting those, spikes caused by technical or other mistakes, central bank behavior, greed is a bad thing. Each move retraces and if you are able to replace greed by a logical based plan to realize your profit, having a sustainable edge, you're at the highest level.
The line is located exactly, where you have no plan except "let winners run". Depending on the timeframe, you're trading, price never will move without retracing. And sometimes a retrace will be start of a reversal.
So your plan always has to have a headline like R/R. It's "only" to decide (the most hard part for sure), which instruments yoi'll use to secure your profit, i.e. fixed trailing stops, fibonacci and/or pivot lines etc.
Greed is an emotion out of control which can influence your trading badly. Find or create yourself a strategy and stick to its rules (and money management) to get over emotions (including greed) during trading.