Bitcoin was really hot in 2021, but not the way you might think.
I'm talking about the massive energy and carbon footprint that has bloomed up as the Bitcoin network continues to grow. We've finally started to pay attention to it in 2021, with Elon Musk calling its energy consumption "insane," and calling into question its usefulness (and interestingly neither Tesla nor Musk have divested themselves of Bitcoin holdings).
It's true that Bitcoin uses an absurd amount of energy, and 2021 was the year that it truly skyrocketed, rising from somewhere around a 77 TWh/year forecast in the beginning of the year to more than 200 TWh/year by December 25. At this point, the Bitcoin network is burning through the same amount of power and fuel as some medium-sized countries, and an individual transaction eats up more power than an average U.S. household uses in 70 days!
Bitcoin, and other cryptocurrencies, need something big, like a transition to proof-of-stake, if they're going to survive a larger global transition to greener energy.