While others were busy analysing the market, these guys acted promptly. Put that into perspective now; ETH has since reach a new ATH since then and hasn't returned to that "bottom" after those moves.
Taking the right action at the right time is crucial for generating a profit from trading and investing. This is part of what veteran traders do; some traders delay their action first to verify the decision they are about to make. These savvy traders have developed their insight so that they can foresee price movements.
Trading is hard; you have to see these minor actions as part of bigger patterns and insights that only develop after years of trading, gained through both losses and winnings.