I have been following this for a while. there are a few times ico is 5-10% cheaper than secondary market, but most times ico prices are higher. I can think of thefollowing reasons:
1 people underestimate last minute contributions
2 eos team or affiliate manipulate ico
3 someone want to buy by volume
4 some buyer dont borther opening exchange account
5 traders and ico buyer are separate/different group of people, based on 4