Their 2014 focus report is available on SEC.gov. They reported just under $800k in assets with capital contributions of around $77k subsequent to the filing.
They've raised over $60 million, probably a lot went into the product (i.e. mobile app) and marketing, however I'm not sure how much they gain in terms of net inflows in 2015. They apparently cater to tech-savvy millennials with iPhones who are able to open small cash accounts.
Zecco Trading once had a similar model, and was purchased by Trade King. Zecco was unable to survive with a $0 based commission model, and Trade King acquired their customers.
Ya, give it a few years and perhaps they will "change their model." As entrepreneurs, they definitely get credit for entering a very competitive space.