The controversial tech figure claimed in 2017 that bitcoin would reach $500,000 within three years, pledging, "if not, I will eat my d**k on national television".
At the time, bitcoin was worth around $2,000 and by the end of 2017 was valued at close to $20,000.
A price crash in 2018 was not enough to deter him and as bitcoin began to rise again earlier this year, he tweeted that it was "mathematically impossible" for bitcoin to be worth less than $1m by the end of 2020.
Over the last seven days bitcoin has fallen in price by more than 17 per cent to around $10,500 but remains well up from its price at the start of the year, when it was trading at around $3,500.
In response to the latest losses, Mr McAfee tweeted: "Bitcoin is at the mid 10's and people worry. LMFAO!! Why do you pay attention to weekly fluctuations? Look at the past few months... It's rising drastically."
He added: "I'm still positive about by $1 million BTC price by the end of 2020."
Mr McAfee is currently residing on a yacht in Cuba with his wife, dogs and security staff after fleeing the US to avoid paying eight-years worth of income tax.
"I'm mad as hell and I'm not taking any more s*** from corrupt-to-the-core government agencies," he previously told The Independent.
He is currently seeking the Libertarian Party nomination to run for President in 2020 and says he did not pay tax for ideological reasons.
Having sold his eponymous cyber security business, Mr McAfee has since turned his interest towards cryptocurrency and has become a well-liked figure within the space for his vocal advocacy of digital currencies.
He recently offered to help Cuba create its own cryptocurrency in order to get around crippling economic sanctions made worse under US president Donald Trump.
Bitcoin is at the mid 10's and people worry. LMFAO!! Why do you pay attention to weekly fluctuations? Look at the past few months FFS! It's rising drastically. I'm still positive about my $1 mil BTC price by the end of 2020. Alt coins like MTC and Apollo will rise ten times more.— John McAfee (@officialmcafee)14 July 2019
In his latest tweet, Mr McAfee claimed that other alternative cryptocurrencies would also experience significant gains, with "the world's first all-in-one cryptocurrency" Apollo among those cited.
These predictions come in contrast to other outspoken cryptocurrency figures predicting that only bitcoin will benefit in the next major price surge.
Financial journalist Max Keiser recently suggested that the altcoin phenomenon is over, with investors' cash now flowing almost exclusively into bitcoin.