Another big flaw in your arguments.  Your posts all assume that the price of bitcoin is driven by production cost, but it is exactly the opposite.  The price of bitcoin is actually driving production cost.  Your $500-$600 figure all include the mining equipment costs, and what determines the equipment costs?  You think the makers of these equipments price them according to their material cost? Yea fat chance.  Why do you think BTC miners are all being sold/bought in BTC?  Or at least priced according to BTCs?  

Furthermore, cost of production in no way prevents a coin from dropping below production cost.  Let's say something catastrophic happens, such as bitcoin gets attacked via 51%, or has a major fork, what prevents it from dropping below this magical $500 threshold of yours?  And you think your miners will still cost the same amount of BTCs compared to before this drop? 

Why do you think all scrypt PoW coins drop in value so much lately such as aurora or doge or any other PoW?  You think it's because the cost of production is low? Tell that to the thousands of people that bought the gridseed blades for $1600 just a couple of months ago.   

Value of BTC comes completely from confidence in the coin, just like any other PoW or PoS coin.  But people's confidence is a lot higher in BTC than any other coins because BTC has been out there much longer.  And if BTC falls below $500, the miner prices will adjust accordingly. 

And stop talking only about Bitcoin in your arguments.  This guy created his long winded thread to tout all PoW coins.  Why are most of the alt scrypt PoW coins dropping despite the production costs?