if most of people buy when its going down then its gonna go up very soon enough and that's mean it's not going to go down in the first place. However, it's mainly because most of people feared that their money will turn into dust when bearish and FOMO when bullish, that's the only reason for that in my opinion.
I think when the market goes up, the psychology of investors becomes more comfortable, and that is when they are easy Fomo so this is the reason why many people lose money. I'm not too fond of the coins that are mentioned too much because it can be a trap for people to invest in and after buying the coin will usually tend to decrease immediately. Before you do anything, you need to think twice before deciding.