so doing some maths, if the avg btc gets to 136$ over 24hr period this will equal the maintenance fee
1Th/s = $1.555/day earning @ current difficulty and btc = $136
[...]
Let me know if my maths isn't correct
You're correct.
1 TH/s generates roughly
BTC0.01144 per day at the current difficulty, and with a maintenance fee of $1.551 an equilibrium is reached at ~$135.61.
Mining at a loss does not imply selling at a loss. [...]
...what does that even mean?
If you're mining at a loss, you're essentially "buying" Bitcoin at a higher price than you otherwise could on the market. If, for example, mining a single Bitcoin has a prime cost of $200 (energy, space, cooling, etc) and the current price per one Bitcoin is $180 on the open market, it makes more financial sense to power off the mining gear and purchase Bitcoin directly. If you choose to sell that Bitcoin you just mined, you'd end up with a loss of $20.