It absolutely has nothing to do with "free market". Fiat currency backs the military, and the military backs the fiat currency.

When people think of the environmental impact of Bitcoin and compare it with fiat, most would think in terms of simple arithmetic. How much energy is spent on Bitcoin mining, how much is spent on the banking sector etc. Whereas, the real cost of fiat is the destruction of ecosystems, air and water pollution, chemical and radioactive contamination, and an endless list of other ecological damages. (And of course all those millions of innocent people dying in the name of the fiat currency.)