Just compare these two scenarios:
1. 1 million users, each one running bitfury's USB miner, electricity can be ignored, 2GH per user, that is 2000T hash power
2. A big mining farm, 1000 machines, 2TH each , same total hash power, but the electricity and cooling cost, together with rent of the hosting location etc will cost them a fortune to mine coins. If the difficulty is enough high, sooner or later they will be forced to shutdown due to cost higher than mining income (they can simply buy coin instead of mine)
However, if the mining farm sold those 1000 machines to many customers, they will easily collect enough coins through their sale. But the miners who receive those 1000 machines might not be able to mine that amount of coins during its life time. This has become the norm in ASIC mining era, almost no one have ever get their bitcoin investment back by purchasing ASIC mining rigs
So it is always better to sell the mining rigs to millions of users, and this will also increase the decentralization of the network
You do realize bitfury make a big profit on USB miner right? What if bitfury, or another company like bitfury, mines themselves. Their hardware costs would be 10% to 30% of the people they sell to.
And the idea that everyone running USB miners is getting free electricity is total nonsense.
