Citi has highlighted the accelerating advancements in quantum computing as a significant threat to the security of cryptocurrencies and internet infrastructure, with Bitcoin being particularly vulnerable. Analysts at Citi noted that Bitcoin's conservative governance and slow protocol upgrades make it less resilient to quantum-resistant updates. Approximately 6.5 to 6.9 million BTC, representing about one-third of the circulating supply, are at risk due to exposed public keys susceptible to quantum attacks. The report also mentioned that Proof-of-Stake (PoS) networks like Ethereum might adapt more easily to quantum-resistant cryptographic solutions due to their flexible protocol upgrades, although validator keys still face potential risks. Despite these challenges, Citi believes the industry can adapt through post-quantum cryptography and protocol restructuring.