However, you lost BTC. The BTC price paid for said items at the time they were bought is greater than the BTC they have produced.
Well, no, that's false, but hey don't let facts get in the way of a good argument.

I've never bought BTC for fiat, every BTC I've mined has been reinvested or cashed out to fiat.
Thus your profit is less than if you had simply bought BTC instead.
(also you need to subtract the running cost and time mining that would not have been necessary if you only bought BTC)
Agreed on the first point.
However, my running costs are essentially zero when averaged out across a year, and over the year I've been mining I've spent essentially nothing in fiat to keep my BTC production around 1BTC every 6 weeks. 1BTC every 6 weeks means I can keep up with increase in difficulty by buying new hardware, and sometimes my older hardware is sold to top up that BTC fund - I sold my 10 Block Erupters and bought two BlueFurys. Selling the Blues paid for the 10 Antminer U1s. Without spending a fiat penny I've gone from 3.3GH to 5GH to around 20GH.
You also have to consider that I'm not really in this for profit. I have a good job that pays me enough that I live comfortably and have enough left over at the end of the month to not only save, but spend on my hobby of building PCs and buying little things to tinker with. Mining is a hobby. Some people play games on XBox. Some people go and piss £100 up the wall on a Friday night. I mess about with my miners.