With some rough math Aaron Toponce comes up with an estimate for Bitcoin Mining Rate and Waste:
At $0.15 USD per kWh, that’s $609 spent on electricity per Bitcoin mined. Bitcoin is currently trading at $376/BTC.
Using the ~$600 cost in electricity for current mining rates, Bitcoin would need to go back to the highs of 2013 and 2014 to have a net positive value.
Aaron is very direct in his conclusion:
I would argue that Bitcoin is the worst idea to come out of Computer Science in the history of mankind.
If this depends on the price per Bitcoin, then this conclusion needs to have more flexibility. It may be that we are too early in the history of Bitcoin to write a conclusion.
In terms of overall issues with Bitcoin, I don’t think this one is big enough by itself to kill Bitcoin. Combined with other issues though, it may prove unsustainable over all.