"Bitcoin Is a Bubble That Will Pop" — Jamie Dimon (2017)

Jamie Dimon's 2017 fraud accusation and collapse prediction for Bitcoin ranks as a historic misjudgment that underperforms #5's spam prediction in terms of long-term reversal. Despite his warning, Bitcoin's price surged from $1,000 to over $60,000 by 2021, while JPMorgan later launched its own blockchain division and a crypto-analytics unit. This pivot from condemnation to participation makes Dimon's call 50% more ironic than the average banker's crypto skepticism, as the asset class matured into a $2 trillion market he now actively engages.