ICO means that you can buy a coin, token or a stock before it goes public. Many of the projects you can find on Coinmarketcap are from the pre ICO times where there was just an announcement that on day X there will be start of mining of that coin. Usually the creators premined some of the coins and the rest was just mined out by users. Then trading started and the price discovery process had begun. When you invest into an ICO it's worth what it's worth! If a project collects 5000 bitcoins it's worth 5000 bitcoins. They have that hard value and from now on it can only grow, right? So the first benefit of an ICO is that it's really unlikely to be worth less when it hits exchanges.