Tell me what is the reason for such a major drop from 120 satoshi to 18 in HyperStake (HYP), is this due to the general situation on the market or with uncertainty among investors in the coin?
The short and simple answer is, more sellers than buyers.

The market fluctuates which is quite normal.
The long answer is a bit more complex, but generally when market leaders like bitcoin begin selling off that causes a chain reaction that affect other cryptos. Everything is connected in some respect. Pschology, emotions....etc... all play a part. Cause and effect.
Does it mean that the underlying fundamentals of the project changed? In this case, No