And this ladies and gentlemen, is a prime example of the Tragedy of the Commons.  A miner quitting as it's pointless mining for a return of cents per day is sarcastically thanked by other miners still in the game, who get very cheap or 'free' electricity.  Other miners are now less likely to quit as someone else will take their share, and it's a race to the bottom from here.

In reality we don't need any miners.  There are 7 million bitcoins in existence which is probably more than half what will ever get generated (early adopters who mined and thought the whole thing to be pointless and deleted their wallet, hard drive crashes, stolen and reformatted computers, deceased bitcoin owners not informing anyone of their wallet, etc).  More than enough bitcoins out there to satisfy speculators.