Here is a discussion from 2011, when bitcoin was much easier to mine, but worth a lot less:<p><a href="https://bitcointalk.org/index.php?topic=8405.0" rel="nofollow">https://bitcointalk.org/index.php?topic=8405.0</a><p>Back then, when bitcoin was about $5, one guy was able to mine 0.38BTC (~$2) in 9 hours for $20 of EC2 time. Now that bitcoin is over $1000, you might think it is profitable, but mining has become more difficult than in 2011.<p>Bitcoin mining is designed to get more difficult over time...like listing the prime numbers, where the 1 and 2 digit ones come easy, the 3 digit ones get tougher, and so on. Intuitively, I would say that if you could put $100 into some new mining technology and get $150 out, then everyone would do it, and the low-hanging fruit would quickly dry up, and soon you'd be putting $150 in to get $100 out.