This is a very nice question that deserves a well defined answer, DIP season refers to a particular period in time when investors have to invest into something (For example, Bitcoin) as soon the price value decreases to a point beyond normal volatility. The price of Bitcoin can drop from $63k down to $61k and we do not call it DIP, instead we consider it as it's volatile nature but when it goes far deeper, hence keep declining in value then it becomes a DIP/ DIP SEASON.

Despite every entry price when dealing with Bitcoin is always said and proven to be profitable, there is always a point where the urge comes into investing massively due to encountering the price at a much lower value, it becomes unsual cause there is every tendency of going back to its previous all time high or probably exceeding it. So investors are luckily and in a rush to accumulate once the DIP season comes.