Is it hard to know when will the crpto price will peak again if no, what are the ways that you do to know the peak in the market?
It is hard to know when a cryptocurrency will peak because no one can predict the next movement in the market. There are no ways to know this.
You can try to analyze the charts, gather info and apply TA to the cryptocurrency market movements so you can be one step ahead of the market, though most of the times these type of analysis will only help you speculate since they're not always accurate.