0% trade fees? How are they going to earn to keep up?
They underwrite ico's, also the CEO of cobinhood is some guy that developed a really popular streaming website in asia.
So he's got enough funds, they intend to get 5% of the tokens of all underwritten ico's and earn interest/fee's on the margin trading.
For the time being though they only make profits on the margin trading when its live - as all underwritten ico tokens get passed down to the holders for free (currently cybermiles)
^ its a super easy marketing method that can steal market share.