Crypto market is very dynamic and what was good in 2017, right could not work. For instance - ico, tell me at least one good ico in 2019? IEO is more profitable because exchanges list them very quick and pumping the coins, which is in their interest.
Highlights always change every year and as you say, 2017 is the sublimation of ICO and the profit of investors is super huge, but 2019 is a removal and change, the IEO appears, providing greater safety while ICO is losing its heat, and of course, the young man that year became older, the newborn boy became a young man, who is better, it is too obvious. But considering at the same time, it is still difficult to predict the outcome between the ICO and the IEO