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BTC price doesn't depend on the production cost. Market sets the price at which one is willing to purchase BTC not miners at which they're willing to sell BTC. Market couldn't care less how much in electricity it took to produce 1BTC, simple supply and demand, where supply is fixed
the main sellers are miners...
If 25 BTC changed hands every 10 minutes, you'd have a point. I believe the value is somewhat greater

Edit: Less than 50 BTC, to validate your "main" claim. I guess they still could be "main sellers" if the other sellers add up to < 25 BTC.