Bitmain is making money on selling the devices

To clarify how it works the router mines like a solo entity. This means that it is trying to solve the hash computational problems on it's own. The likelihood of this little guy being able to do that before any one of the massive pools of hash power does is.... closer to 0 than getting in the Powerball (which I believe is around 1 in 200m but even that may be low)

So it is a lottery in the sense that you are trying to be the 1 person/device that "gets it right" before others do, but it is not a lottery in the sense that Bitmain pulls a number from a hat and you win if your router has that number

Hope that clarifies @sames @btcupload

Also props to @darth-azrael you made me LOL