If the hash rate increases it would just be cancelled out by a rise in difficulty due to blocks being completed quicker across the network.
So realistically, unless electric comes down in price or Bitcoins increase in value, this isn't a valid investment opportunity really is it?
This sums up very well what I think about mining:

We are the donkey and the carrot is a bitcoin network. We can try to get a faster donkey, but the carrot will always be ahead.
My point is the network always corrects itself. This correction may not be sudden (there are periods of higher profitability than others), but in the long term it evens out. That being said, maybe you can take a few bites at the carrot, but you won't catch it
