That is tje commom peoblem that an investor or a trader is always experiencing, I've solved that by picking the cryptocurrency or altcoin that has a huge market capitalization nand volume, those that are frequently traded by most of the people, because one other thing I'v nlticed is that, if we tend to sell our altcoin with profits, it takes a very long time for people to buy it if there is an insufficient traders who use the crypto you have. But, with good cryptos, you can just ride woth the whale and you'll surely have profits everytime you sell it.