I do some investment in altcoin, but yeah ICO is really promising. But just becarefull, not all ICO is save some of them just want to take your money away. And remember even if the ICO is real and have working project the price of the coin can decrease significally after the ICO.
Yes, I totally agree with you, investing on pre-sale and participating in ICO will make you huge profits as there are many bonuses or discounts, its just that it is very risky because many of them are frauds. You must research everything to know about that ICO.