Would anybody like to speculate on Circle's business model?  They didn't throw millions of dollars into this to have a completely free service. Is the only money they are making on the spread between exchange rates for buy and sell orders?

I suppose that could be enough to cover the credit card fees, the merchant fees, the miner fees, and their overhead.

They lose money on each transaction but make it up in volume right? 

Can the make a profit on the spread?

Or are they just trying to grow market share and then sell ancillary, yet unannounced, services?