The same goes with mining, it is not profitable anymore for you to mine coins at home, it must be done with ASIC and in a large scale to be profitable over time.
Why has it to be done in large scale to be profitable?
It doesn't make any difference if you run a "small" 100GH/s at 100W machine or a "big" farm with 100 TH/s at 100 KW. (Numbers pulled out of my ass, no Idea what the current specs are)
Well there is one difference: While a small miner can run their equipment at a loss and just for the fun of it, the big miner will be forced to shut down when the cost of mining one BTC becomes higher than the price he can sell it for. You maybe can stand a few dollars of loss due to power cost each month, but when it's 1000nds each month there is no choice, you'll have to shut down.