The problem is you have to account for the difficulty, which has changed. It looks like he was predicting a block per 78 hours, while it is now closer to 2/3 o

The problem is you have to account for the difficulty, which has changed. It looks like he was predicting a block per 78 hours, while it is now closer to 2/3 of a year. Looks like 1.64 GH/s = $10.66 a day roughly, compared to a cost of $400 a day.