IEO is somewhat profitable because it is already listed on the exchange and trading begins immediately which gives it the chance to grow on a fast pace unlike ICO that takes a long time to get listed on an exchange before trading begins.
But even if its already listed you cant still guarantee that their price can rose imediately because they are still volatile . plus , you can instead expect that their price can fall down evenly because the chance of dumping them is too high since they are already listed . while on ico ,you can expect that the price of the coin can instantly pump after it gets listed since investors and bounty hunters were only hodling thier coins for a long time .