They said that they have big investors backing this project and ready to buy all tokens and that's why there is only 20% of total supply for public sale. So I think there are a big investors behind the sense who brought a big percentage for some privileges and good discount.
I'm not sure but 20% for public sale is a normal amount for an ICO while there is a big percentage in the private sales, it served for a bigger investors which hold the coins or tokens for so many years.
Dude, big investors are not stupid to hold a token or coins for many years like some people believe, the word itself is tricky, because it can refer for an investor who buy big amount or for investor who investors large amount of money and has a private deal with a company with some privileges, he is not type of person who gets tokens on his wallet waiting years to sell on exchange.