People acting been greedy as you said are the ones that are experienced in the crypto market and knew exactly how it works, maybe they've missed the bull run many times and had promised themselves never to miss any new upcoming ATH by any means necessary, no matter what it takes and how long interval it might go to reach their target.
It's not always easy to be that patient when you are new in the space because those users aren't conversant with the movement, especially those that criticized the guy that wants to sell at targeted price, those users are new so they call him greedy.
You have a valid point mate. People who understand and have experience with the Bitcoin market circle will be more patient than newbies. A newbie will be influenced more by FUD and can also be affected by greed. You are also correct that a lack of knowledge about past bull runs might be why some people see another investor as greedy.
But it is necessary to state that we cannot predict the time Bitcoin will hit ATH. That is why I always advise newbies to set reasonable targets. It was generally predicted that Bitcoin would hit $100k, so newbies should target such a reasonable benchmark.