When bitcoin is at low price we are afraid to buy because we think it's going to dump more but when its price goes up we don't know where to buy at the proper price. FOMO is difficult to control, what I do is when I already bought it at somewhere at a high price I avoid looking at my price tracker app. And I think people that are most affected by this feeling is those who can only buy using their extra money. They won't afford to buy again if price goes down more.
Actually, this is the problem of new investors. A lot of people have gone empty-handed and lost big due to psychological factors when trading. So to trade successfully, we should spend a lot of time on understanding how the market works, crowd psychology and some tips to recognize whale manipulation.
I've had a pretty good year realizing whale manipulation in March of this year. Before the Bitcoin Halving event, the whales intentionally sold it off so everyone was scared and sold it for no reason. I was calm then and bought a lot of ETH at the prices of 98 $ and 116 $.
In order to stay calm as I am now, I experienced many failures and read a lot of literature on how the crypto market works. This is one of the very important knowledge that any holders should understand. So I recommend reading more about the Dow theory to get a cooler head and prepare for the strong bull run coming.