Those were foolish investors who left the market of Bitcoin because low market price does not mean that it is going to end but it can recover from low market into normal market price and then up to high market price.
Since we know that it is a long term investment so we should not treat it like short term that results in wastage of time and clear loss. Low market has its own benefits and I know one major which is to invest further more in low market on low price. Bitcoin will keep rising in coming days hopefully as many people are predicting a new ATH before end of this year.