My mining rig only cost me $480 with a 6870 and 5770. I will recoup my costs in less than 6 months. It is still profitable.
but what would $480 of bitcoins bought when you bought your rig be worth today?
how many more btc would you own today if you had bought btc instead of mined? and current value of that 'btc gap' ?
add electricity costs and subtract current value of the equipment to determine if you're in the red or black.
no one's saying that you can't make a profit - just that the more the price goes up, you more you have lost 'potential revenue'.
it's as if you are betting that price won't increase much if you buy gear instead of btc in the market.
the good side is that if the btc are worthless tomorrow, you still own a computer and only lost some of its value.