It depends on the coin, if you want to sell it or invest. Fro the current situation right now of the market most of the coin are on its low value but if you know that the coin has a good future you can invest on it or hold it because the time will come it will rise again
in cryptocurrency market there are more than 2000 coins/token .if we could pick the best one of them i think its be great opportunity for us.moreover sleeping giant coins that have huge potential in future.its has good roadmap and developtment but they still lack of investors.and need support from investor.maybe investing in this kind of coins give us profit.
At least if we can pick 10 profitable coins, we can have the opportunity to gain much profit. At this moment, if we can buy any coins at the lower price, then it means we are investing in that coins which we can hope to make a profit in the short-term or the long-term. But still, I don't want to sell any coins which I bought in 2018 because the price was not yet reaching the price now and it's too low to decide to sell right now, and it's better to wait for a while.