This makes sense, but you may be leaving out two relevant (ASIC Mining gear) market segments:
1) New Bitcoin investors that prefer to mine their coins instead of buying them (there are different reasons for this that have been discussed somewhere else)
2) "Corporate Miners" that need to stay on top of the game
Also, you should be very cautious when declaring the whole mining industry "not profitable at current difficulty levels" - as long as Bitcoin prices keep moving they have, it will be extremely difficult to prove this assertion. Looking at ROI in BTC alone can be an extremely misleading simplification.
I somewhat agree with the above paragraph, but the following one seems just wrong: since you pay the device in BTC, you have to consider only the BTC itself: exchange rate with other currency is totally irrelevant, since you had anyway the option of "just keeping your BTC" and having them appreciate exactly the same.
I'm quite tired of having to explain this time and again, it's so obvious but people keep getting it wrong. Will they ever learn?
You are wrong. Your pretentious attitude sucks.