Nope you are wrong, many projects dumped after IDO because investors want to take profits and those projects that have discount price at IDO even dump more, if I want to invest in a good project it will be after the IDO not before the IDO.
That means if IDO was very profitable for the early investors as you said that if they able are taking the profit. You must also remember that if someone able to take the profit after the token listed on the exchange site and this means if IDO was very profitable for people who have been invested at the early stage. I think that you are wrong about that. You must also see how profitable IDO for the early investors.