There are whales who always ready to take the advantage of our unawareness so when they start to spread bad news in market they become so active whoever wants to sell they will be ready to buy, so same as you I got to learn that no need to listen them and selling buying should be done with my own observation and with patience.
Those are not whales but pump and dumpers. Again someone can be both as dual personality - you never know whats happening with every username on the internet. Sometimes prices are getting manipulated like that.
Fear, greed and so on are of course bad, but sometimes you need to allow it, to a certain extent, to achieve the best result. Because if you do not want to achieve something more, you can remain with nothing.
Dont think thats what the topic is about but yes in general it is correct that fear and greed are part of the market psychology and this will teach people to fall prey of emotions and take a wrong decision only to regret it. In being a successful trader one will make mistakes but they can be rectified in future or prevented.