I open CEX.io and find this rather confusing price:

GHS/BTC = 0.00747 which is the equivalent to THS/BTC = 7.47 = 4.487 USD

So you need to pay more than 7 BTC for one TH/s? It does not make sense at all. Here's why:

Currently one TH/s generates BTC 1.12 per month = 667 USD.

Don't forget maintenance. One TH/s costs 260 USD per month, reducing the profit to 407 USD, so it takes 11 months to break even. With difficulty increases it will surely never happen.

Am I right?