Another possibility is that people that got early and got huge bonuses have decided to sell, even if they have to sell for a lower price the bonuses they got may offset the losses and in some cases they may even get profits, that is why I think it is a bad idea to give those bonuses since an early investor can dump his coins and profit but by doing so it is affecting the users that bought later in the ico since his actions reduce the price of the coins for everyone not only for himself.