there was a saying is that ,btc's price can not drop down bellow its mining cost.e.g,if btc's mining cost is 5000 $,btc cant drop bellow 5000 $,if the price is lower than 5000$ ,the mines could be paralysised ,so btc transacion cant work either.the statement sounds reasonable.to avoid this situation ,btc's price must be above its mining cost.
On other hand, the difficulty of mining btc is growing harder and harder ,if one day the mining cost goes up to the moon ,e.g, 100,000,000 $,would the price of btc  also go to that level of price?but the height of price cant be maintained that high,people would of course change their btc to fiat currency,so i think its quite contradictory to ballance btc price and the mining cost.what do you think of this paradox?