For a starter, I hate been redirected out of forum to go read some article, if you're the original owner of article then post then on forum and you can add a source link at the end for reference purpose or indicate you're the original owner of article to avoid been accused of plagiarism.
In addition: There's a disadvantage I have noticed in the past project that carryout their crowdfunding through IEO which is very disturbing. The whales are manipulating the sales, they buy all the token in matter of sec/mins leaving the average investor with no token to buy which is bad because this guy's can easily manipulate the price of this coins/tokens when they hit the market. Exchange need to find solution to this issue which could be solved by putting buy limits on each account.
Kucoin has taken anti-tool measures to buy the tokens of some whales but it is still ineffective when they have promptly modified the tool.
Because of the whale's early token manipulation, the IEO projects are now no longer as original. Bittrex's VBK is now at the lower price of the IEO.
This is a sign that the trend is ending and we should consider when investing in the IEO.
The source of earnings is exchange, not IEO. IEO was not trend, after binance's several successful IEOs, others also joined, but they failed. I guess, binance also will not be able to continue until end.