They don't produce anything except some numbers. A total waste of energy. I had to laugh when this guy I know who is very "progressive" and environmentally concerned got pissy when I pointed out how much energy was wasted on bitcoin mining just because he was into it.
Misleading title - the problem is not "crypto", it's pretty much all Bitcoin and the people against the change in the consensus mechanism. Out of the top 10 9 coins in market cap, Bitcoin is the only one using proof of work, which demands such high energy requirements.
Ultimately, mining should be banned from the surface of Earth. Let miners build orbital solar panel infrastructure close to the Sun where power is plentiful. See Bitcoin developer Peter Todd's 2017-09-10 presentation on the subject (transcript).
Just a PSA that the second biggest cryptocurrency by market cap (ETH) is no longer proof of work, and in the process, reduced their power consumption by ~98%.
"Research has found that bitcoin miners alone consume approximately between 60 to 125 TWh of energy annually, which is equivalent to around 0.6% of global electricity"
"Traditional banks' total annual energy consumption of traditional banks is around 26 TWh on running servers, 26 TWh on ATMs, and 87 TWh from an estimate of 600k+ branches worldwide. Totaling 139 TWh."
Not to mention banks impact on people's lives. Limited purchasing power of the poor and soon to join them middle class.. to purchase disposable products
I've always found this argument against crypto to be a bad one. The headline will say something like "Crypto mining uses XYZ total energy" and we're supposed to infer that this means crypto is polluting a lot. But it doesn't say how much pollution there actually was. For economic reasons, these miners often use cheap excess energy that would have been produced anyway or green tech. Not all of it obviously, but that level of nuance is missing.
Also, we don't make the same moral arguments against other energy uses. Air conditioners use more energy than Bitcoin mining does, but we don't go around saying the government should ban people from using AC.
There are legitimate problems with crypto, but this one never convinced me