If you buy a mining contract and hold it, then it probably won't be profitable because you will end up with less bitcoins than the amount you put in. If that is your goal, then I agree it would be better to simply hodl the bitcoins themselves and your calculations seem to support this conclusion.
What you are forgetting is that you can profit by trading the mining contracts themselves.
What you are forgetting is that you can profit by trading the mining contracts themselves.
This is the definition of a bubble
Yes, you can trade and make a profit, but over all it is a negative sum game. Better play roulette and get 95 cents back for every dollar on average. You are more likely to win there too.
Even worse, by speculating in GHS you enable miners to use Ghash at no fee. I think they actually accept miners for free because some miners convert their revenues to GHS.