Why the last one ever? If you have that big a hashrate,your earnings won't be going anywhere.
As difficulty goes up, the revenue (bitcoin mined) will go down.
Eventually, the revenue will not be enough for OP to pay the rent
That was my point. With him having a large enough hashrate to pay his rent,the difficulty increment can't possibly affect his earnings in a substantial way.
Maybe his hashrate is not that big, and the revenue can only marginally cover the rent this month.