Bitcoin is down about 59 percent this year.
The environmental cost is too high to make crypto a good choice for anyone who cares about the planet, says Tara Shirvani.
Bitcoin miners are putting as much CO2 into the atmosphere as the entire city of London for the benefit of "almost no one".
Bitcoin, the world’s biggest and best-known cryptocurrency, has fallen 26 percent from the year's high.
All digital coins combined have a market cap of around $1.7 trillion.
Musk has backed bitcoin, a digital currency estimated to cause more pollution than a small country every year.
"He's gone off the rails."
Elon Musk's Tesla car company has invested US$1.5 billion in Bitcoin and plans to accept it as payment.
The digital currency almost almost quadrupled in value during 2020.
