I'm saying this because it is real. Just imagine, Ethereum has built many tokens inside the blockchain and many people launched ICOs which most of them are totally weird and fake, but some of them are not. People usually like to trade their ethereum and turn it into a token where it can be determined as a "future asset" and it cannot be sold until they had listed on an exchange. The companies who launched the ICOs are usually selling the ethereum which gotten from their ICO in droves, in which it can make a dump on the Ethereum market.
May be but in other way Ethereum and ICO boom was one of the main reasons why market grew in 2017, so if there weren't icos, may be we would never see bitcoin above 3000.