It really depends on the coin that you are talking about, if we are talking about bitcoin I do not mind holding no matter what, in fact I held my coins during the last crash that we saw and I didn't have any kind of problem with it, but if the money we're talking about is one that I'm using for trading then I have a very specific amount of money that I'm willing to lose in each trade and as soon as that amount is surpassed I sell my coins.