I agree with you, uncertainty regarding the future outcomes is the biggest reason for not holding the coins, The most losses of investors of gains is investing on scams coins or selling too early on promising projects, Then boom, out of a sudden news leak on reddit and the price hikes basically overnight. Since you cannot time these it can be a good strategy to simply say "find a coin you believe in and just hold it for at least several months - it may not go up immediately, but in the long run you will be happy".