> Regarding the environmental impact of the Bitcoin network, while being widely derided for its energy use, it is in fact using less electricity than the major credit card networks. It is also using less energy than global gold mining. There are ways to reduce consumption should a consensus accept the tradeoffs.

That's not the point. The issue is with its growth trajectory.

Setting aside how little Bitcoin network can handle vs. major credit cards per unit of energy used, the "mainstream" financial system treats energy use as waste that has to be minimized. Per constant number of players, it is expected to stay stable or even decrease. Bitcoin treats energy use as a security feature, and is designed up front to grow it continuously. Per constant number of players, it'll still grow fast as the difficulty of mining is increased. Even with growing populations, mainstream system seems at worst O(n log n), and Bitcoin is definitely faster[0].

Another thing is - the mainstream financial system already works, and does its job well. Bitcoin is seen as a way for some mix of greedy and politically fringe types to make money quick, exploiting cheap electricity.

--

[0] - I'm giving a tentative O(n^2) here, I have a feeling it might be faster, but didn't check it. I'd love if someone could list here the sources of growth of energy usage in Bitcoin network.