I am personally a miner, and I keep all I mine. I just sell from times to times what I need to pay for the electricity but that's all. Time said me I was right and with my predictions in the crypto-currency market, I will be right another time.
Yes, you were right. Unlike a friend of mine who mined almost 10 BTC two years ago and sold all of them the same year. He barely covered his expenses on electricity and mining equipment back then, but what if he was holding his BTC until now?