For me I will say that all the altcoins dont have exact time for it to be popular. If the altcoins make some sense people will buy it and make it popular but if the dont make any sense nobody will buy it and thats how it will dump.
I agree, many of the investors who buy altcoins are not for longterm investments, they just take the moment, after that they sell it again, and move again to other altcoins, and keep repeating