http://Toom.im is a 750 kW hosting company with about 200 kW of our own miners and 500 kW of customer-owned gear. We're in the process of expanding to 2.25 MW of capacity. We've got 8 employees right now, a 8000 sq ft warehouse, and a five-digit monthly power bill. We spend a lot of money.
We usually hold most of our revenue as bitcoin. My own primary personal mining address, for example, has never sent any money since I created it. We keep about 1-2 months' worth of expenses stored as fiat. We try to be careful to ensure that, if bitcoin were to crash down to 10% of its current value, we would still be able to pay the majority of our debts and shut down cleanly. A lot of our customers pay us in fiat, though, so typically only about 50% of our monthly expenses get paid by selling bitcoin. Each time we expand, though, we have to liquidate the majority of our holdings in order to pay for transformers, switchgear, etc.