Even at the 1$ it will cover the cost in electricity for 1500 cointerra miners , 1,5 PH of hashing.
No botnet can provide this much hashpower.
So assuming that bitcoin costs $1

Am I doing something wrong?
If no then you are not correct.
And amount of cointerra miners doesn't count in here in sense of profitability.
http://mining.thegenesisblock.com/a/d2332bc1e8Monthly Power Costs: $64.8
You are taking into account acquiring the device.
Well those device have already been paid for. People right now would have the only option to run them.
If you don't run them , you get 0. If you still run them , you'd get a few bucks.
Of course no new ones will be added to the network but those already produced will be there hashing.