All of the investors left the ICO because many ICOs in this market are scams, so they must be more cautious in order to avoid being deceived, and the market is still underestimated. There are many excellent cryptocurrencies that can be invested. And they can also get rich returns and risk less, they are more willing to invest.
No one left the projects, just many are waiting for the global growth of the entire market. As it happens, a lot of money will be poured in at once