Some times we think like greedy and make a mistake for sure.Same I haddone when the price of Ethereum had reached 440$ and expected it to reach 600$ that time.But everything spoiled by my mistake.
I think that's what people call FOMO. Basically afraid of misisng out while buying the coin when bullish instead of when it's bearish and with cheap price.
Most of people also think that way because of human pyschology and that's actually natural.
However that's what not needed when doing trading and could cause heavy loss