IEO was first sarted by Binance and the first token BTT was a hit. It even gave good returns to people who buy it from the exchange after the token was listed, Maybe the reason was that it was extermely cheap and Justin Sun had created a lot of hype for it too. Apart of that most of the tokens give more than 2x on the exchanges including Kucoin, Binance, bitrex etc. Although currently participating in IEO is safe, as you are almost sure to make minimum 2x from it, but which the passage of time, many scam IEO will also come in the market.
BTT isn't a total shit token.
It has the potential to be huge with how BitTorrent could allow hundreds of millions of users to tap into the utility of that token. If they work this out well enough, I am quite certain that early birds will be generously rewarded for their confidence in the token. It's the first token with mass appeal, and it could be integrated in other Torrent clients too.
Every IEO that came after BTT is garbage. There is no nice thing to say about them. Most are pure scams, where some are nothing but an idea the people behind the projects allow you to buy into.