It's a mistake to think in terms of USD profit.
The profit is easiest measured in the currency that you pay your electric bill in. But since they are exchangable, it doesn't really matter.
Furthermore, even if you don't care for Bitcoins, no one is obligated to sell at the current market prices, that's actually the stupidest way to go.
So who is buying above current market prices?
At least for the time being, I think most people/companies who approach mining as business need to exchange the generated coins to another currency in order to pay the bills.