Oversaturated financial markets perhaps?
Who the fuck invests in bitcoin? People with too much money and the habit of gambling.
No one can tell me that there is a logical argument without flaw and a ton of assumptions that the bitcoin market is in its current state anything than gambling.
Because bitcoin is so active and new makes it so interesting for gambling :(
Either cryptocurrency is extremely useful and the energy spent will turn out not to be wasted at all or it is a big useless energy draining scam and the whole thing will soon collapse.
I really don't see a scenario were it will still be useless or only moderately useful and consuming so much energy that the human species will slowly die off.