My belife is that they use, contracts to hedge and buy gear with for one contract they probably can buy more mining equpment for there own use.
This shuld make there farms grow faster than just mining and reinvesting.
Build a farm sell out % of the gear in contracts, mine on your own gear for "free" and still ern service fees and such.
Thats true I didn't think about that, but how big do you think they want to grow? their operation is already huge!