Although around four million machines are currently active and nearly 75,000 blocks are produced every year and a half, Alex de Vries, a blockchain specialist at PwC, believes that 98% of bitcoin mining machines will fail to produce a block during their average lifetime.
The specialist tweeted earlier this week, that less than 2% machines are able to produce a block to verify bitcoin transactions.
He explains that even if you take four years as an average lifetime of bitcoin mining machines, the number is not any better at around 200,000 blocks on 4 million devices.
Energy consumption by bitcoin mining machines is also a cause of concern for de Vries as he believes, the carbon footprint of a single transaction is equal to spending 52,043 hours watching YouTube.