People seem to forget you can't just scale up without spending way more money. Sure the farms might get bulk discounts, but a home miner running a single miner is much easier to manage and requires no extras that a farm would need. Farms need a place to put the miners, shelves, power equipment, wiring, networking, breakers, list goes on and on. A home miner with low power cost is going to have a higher profit margin than a large farm. A home miner with the same miners as a farm may be able to run much longer than the farm. The problem right now for home miners is a lack of choice of ready available miners and the longer initial break even point. Mining for quick profits is unlikely to happen again. You may come across short events like the paycoin fiasco where lots of us made extra coin for a few days, but I doubt there will ever be another large spike in bitcoin price that isn't followed by difficulty increasing rapidly to compensate. Mining will always trend towards barely profitable.