Everything is relative. Bitcoin mining is really an insanely energy-consuming process. However, we should remember that in the case of Bitcoin, electricity is spent only on mining and blockchain operation. While maintaining, for example, a payment system, which is used by almost all people and often enough, is accompanied by additional energy costs. BTC is even more environmentally friendly than traditional payment systems. Also do not forget that the total number of bitcoins is pre-installed. This means that sooner or later the last BTC will be mined and the mining will finally stop.
I agree with you in most of what you've said. The cost of electricity to support fiat, or even mining gold, since many compare bitcoin to gold, is way bigger than the costs used to mine bitcoin. A lot of miners are actually trying to use renewable energy, mostly because it's cheaper, but it's also good for the environment so it's a good thing they are doing it. In fact bitcoin mining could help boost the investment to produce renewable energy.
The only thing I don't agree in your post, and that shows a certain lack of understanding on why mining is done, is when you say that mining will stop.
Mining is used to keep the network secure, by confirming that every transaction made in the BTC blockchain is legit. In order to do so, miners get rewarded with some bitcoin (this reward is halved every 4 years, and the next one will happen in 2020). So when all bitcoins are mined, this will simply means that they will stop getting this reward. At this time, the only incentive they will get to continue securing the network, by verifying transactions will be the fees they collect. So basically mining will never stop.
