If business class tickets become cheaper, financial analysts will not start buying more plane tickets. Bitcoin miners on the other hand will start mining twice as fast the second the electricity price drops by half.
It also doesn't seem like Bitcoin stakeholders are remotely interested in transitioning the system off proof-of-work and towards less wasteful alternatives, or even just making it more tractable as a retail payment system.
Inflation. If you don't spend your money, it loses value. This is actually part of the economic program (inflate to grow demand). What are you going to spend it on? Stuff or sevices. Stuff takes electricity to make. Services take electricity to perform.
You could also invest, but that's also just indirectly incentivising stuff and services, except in a trickle down fashion (put money into the corporation that's gonna do these things).
Bitcoin may be wasteful, but, its energy cost is explicit and not hidden, which is why it's attacked.
How does spending money on clean energy infrastructure produce CO2 emissions? Obviously there is a trace amount because we are dependent on a CO2 based economy but in reality if the incentives were correct we would be able to increase spending without additional CO2 emissions.
The problem begins with the fact that the central bank is distributing the fresh money in a way that drives Bitcoin up. So yes, we could argue that the central bank is directly responsible for the CO2 emissions of Bitcoin and the system itself is what's broken. Bitcoin is just the symptom.
Is it 1/200 of global financial activity?
Coindesk indicates that bitcoin had 25 million transactions versus Visa having 50 billion transactions. So that is 1/2000 [https://www.coindesk.com/what-bloomberg-gets-wrong-about-bit...]
If Visa had a similar energy efficiency to bitcoin, the energy use of Visa alone would be larger than the current global energy use.
This rules out unaccounted dependencies hiding a larger energy use than reported for the financial sector that would put bitcoin on a more even footing, even when you count things like "the US military" or "extracting oil to fuel cars" as an energy cost solely existing for the financial sector.
Using BTC for your savings or checking account would be an absolutely terrible idea given its volatility. No rational person would ditch traditional banking in favor of Bitcoin.
So really, this is just whataboutism to deflect from the fact that, environmentally speaking, Bitcoin is one of the worst inventions of the century.
There are people who have made arrangements to receive their payroll disbursements in BTC.
While there are not many of these people and they probably all still maintain some form of traditional bank account, I am curious if you would define these folks as irrational (by your definition)?
Would you define someone who put 100% of their net worth into an aggressive, high-risk investment as irrational?