There is no one can guarantee if buy coins or tokens during IEO will gain profits as you wish. too many projects dumped after official listing, even their projects look good. of course not all project like that, but if you want to gain profits more, buying when discount is good idea. Let's say, when you find IEO with normal price $0.2, you can buy when private sale promo price $0.1. or with 20% bonus or something else offer.