It really depends, I could tell you from my experience. I invested in 2 ICOS, and they were a total fallout, like I invested about $300 in each, and after the ICO ended the price did fall and lost about 80% (just checked up the prices of the ICO coins rn). So it's not always good to invest in ICOS, maybe you can earn more after the ICO and buy some of the coins for cheap on the exchanges. You should always look at their whitepaper and their plans for the next years. So my conclusion is: Buy on exchanges for low after the ICO ended. But just do what your heart tells you, if you really believe in their whitepaper and you think you'd make big with them, just invest in their ICO.