In my opinion, and just like @bitterguy28 said, your topic is quite off from the content. I don't think this has to do with greed, but rather with the misinformation that some people usually have about the project they have invested in or the project they want to invest in. Some people don't usually carry out research about the ICO or IDO price of a coin, but they would rather believe in what others have told them, without minding if it is true or false.
Also, when you talk about greed, some people are not really greedy, as you describe the situation. If, for example, I buy a coin when the price is at $0.04 and perhaps the coin falls to $0.02, there's no way I will not feel agitated.Some of those investors that are complaining probably may not have had the opportunity to buy the coin at a lower price than the listing price, and if they do, what's the assurance that the project can become very successful in the future?