I've only really followed one ICO and the same happen. My assumption is that the people who got a first day bonus of sort were able to make a profit.
The cycle will always repeat to the next ico because majority of early buyers, investors, speculators are expecting to get early profit and they can go out as fast as possible with the help from the liquidity that will get by the coin when it can give them more than 3x from the ico prices.
Investors are looking for something that can give them easy profit.
The bad part is that it's probably just a few on the investors. Like 5% who do that and affect the price.