It is correct that on trading there is nothing loss until it is panic sell but if the price drop too much and it goes to to below and don't recover then it remains loss though it is not sold. Also there is no way to recover for example ,if we consider about the luna than it will be clear about the loss without selling. Though the value is not 0 but it is near 0 and there is no chance for recover.
I will say that panic sell and also the panic buy I mean the FOMO(Fear of Missing Out) in this case you will also buy a coin buy emotionally like it's is going up may be I will be in back side if I don't buy it now so that I will miss the chances to make profit. Here also trader make mistakes and also face losses.
So I will say that not only just the panic sell traders also face losses if they don't buy on the correct time as well don't select the correct coin like as you mention the name LUNA, it was in the top four once and what happen is now? It goes vanished from the market. So we also should take cares of these things.