For short term trading, volatility can provide opportunity. However, volatility also means that short term plans sometimes go awry. Certainly there are some, but many sold, or had a small position to begin with.
Many people do.
It's too easy to assume you would still be holding it all. It is natural. But using it as a motivation for the next investment is a mistake. More often than not, if you had, it wouldn't have. Sometimes you find a repeatable pattern that works.