The crypto world is not different than the regular financial markets and the consequences of emotional trading can affect strictly trading performance. The fear index is a good indicator of buying low with the idea of buy when everyone else sells. Greed index is also used for liquidating the position when the HYPE goes above the realistic values.
It is worth to use this index and take a look at the same time on the trading volume changes - if it goes up much above what we could see in the previous couple of days, be ready to see a shift of the trend.