It depends on the exchange and the project of course. For example IEOs profit of the Binance is more than X5 - X10. But of course if you can join. I tried many times but I didnt achieve to join. My bad chance.
There is no gift / profit for all investors. In financial games, there are two types of investors, winners and losers. You will be a winner or loser, that depends on two things: which projects you invest in; and the timepoints at which you enter and exit those projects. Those rules surely can be applied for IEO investment.