1. Low Profit
Most of ICO when their token listed in Market/Exchange, that price is always under ICO price. There are 2 ways to escape. Sell with low price and small loss or Hold and wait their price pump.
This is the usual problem I encountered in ICOs, we bought the coins in their said price but then when it get listed, the value is always under ICO price thus you have to wait until the price increase. The worst part is the coin delisted in exchanges so there's no way to take profit.
3. Most of ICO are scam
Its difficult to see good and real ICO. You can't predict what ICO will giving huge profit and success. Not all success ICO is trusted, they can scam too.
That's true, a lot of existing ICOs are scam nowadays and its hard to determine which is which. Hence its important to have a proper research and ask for other experts opinion about the project because its better to be careful.